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Finding the GCF will help you when you are trying to reduce fractions.
Wiki User
∙ 10y ago
Wiki User
∙ 12y agoThere's no trick. Find all the factors of the numbers you want to compare. Select the ones in common. Pick the largest one. That's the greatest common factor.
Wiki User
∙ 8y agoIt helps in simplifying fractions.
Wiki User
∙ 13y agoFor example, to simplify fractions.
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How do you find the common factors and the greatest common factor of two numbers?
you divide the number by itself then you add the same number onto it and then divide by 3. this is a very uselful trick that my maths teacher, mr plunkstick, told me
How can you tell if a shark likes you for greatest common factor?
He takes another bite ;)
What is the GCF of 6 and 40?
Factors of 6 are 1, 2, 3 and 6.Factors of 40 are 1, 2, 4, 5, 8, 10, 20 and 40.Common factors are 1 and 2. Therefore, the greatest common factors(gcf) is 2.Alternate method:The method used above is not useful for finding GCF of larger numbers.However, the method of prime factorization is very useful and simple for finding GCF.Prime factorization of 6 = 2x3Prime factorization of 40 = 2x2x2x5It is clear from the factorization of both numbers that 2 is the GCF.
What are the greatest common factor of 42 and 126?
The greatest common factor of 42 and 126 is 42. For future reference, to find greatest common factors, list all of the factors of each number, find all factors in common that the numbers have, and choose the largest one. For example, The factors of 42 are: 1, 2, 3, 6, 7, 14, 21, and 42 The factors of 126 are: 1, 2, 3, 6, 7, 9, 14, 18, 21, 42, 63, and 126. The common factors between 42 and 126 are: 1, 2, 3, 6, 7, 14, 21, and 42. The largest number in the grouping of common factors is 42, therefore the greatest common factor between 42 and 126 is 42. Of course that's the long and tedious way. Trick: Trial and error 1) Try if you can evenly divide the smaller number by the larger one. That is find a number a such that a x 42 = 126. You can easily find a this case, a = 2. So, the smallest common factor is 42. 2) If you cannot find one right away, divide them by the obvious common factor, in this case, since they are both even, divide by 2. Then try 1) again. But do this only if 1) fails repeat 2) for a while. If you cannot find one for, say a long time, use the long way or You keep trying and reduced it to two numbers that obviously have no common factor, then you multiply all the factors you had from 2)'s and that's your answer (so something like 2 x 2 x 2 x ......x 2 x 3 x 3 x ..... = 42)
Is 24 a factor of 96?
It is a factor (96/6=16). There is a trick that can help you remember if 6 is a factor. It has to be divisible by two (ie if it ends in a even number) and be divisible by 3. The trick for finding if it's divisible by three is to add up all of its digits. In this case, you would do 9+6, which gives you 15. If you do that again (1+5), that gives you 6, which is a known multiple of three.
What is the trick to finding the least common multiple?
Prime factor tree!
How do you find the common factors and the greatest common factor of two numbers?
you divide the number by itself then you add the same number onto it and then divide by 3. this is a very uselful trick that my maths teacher, mr plunkstick, told me
What are the greatest common factors of 55 99 18 45 22 55 36 48 40 50 40 25 84 108 72 80 15 9 0 16 25 40?
trick question, the number zero is in the list, therefore there is no common factors between all of these numbers
How can you tell if a shark likes you for greatest common factor?
He takes another bite ;)
What is the trick to finding the greatest common factor?
The following answer describes four methods of finding the greatest common factor, with examples, and several "tricks" or shortcuts that can make it easier.Method: Guess and RefineSometimes, you can look at two numbers and make a good guess that you can refine.Example 1: Find the greatest common factor of 45 and 50.Because both numbers end in either a 5 or 0, you know that they are both divisible by 5. If you divide both numbers by 5 and the results have no common factors (except 1), 5 is the greatest common factor.45 ÷ 5 = 950 ÷ 5 = 10Since 9 and 10 are consecutive numbers, they have no common factors. Therefore, the greatest common factor is 5.Example 2: Find the greatest common factor of 150 and 750.Both numbers end in 50, so they are both divisible by 50. If you divide both numbers by 50 and the results have another common factor, you continue identifying common factors until you have a pair without common factors.150 ÷ 50 = 3750 ÷ 50 = 15Since 15 is divisible by 3, and 3 is divisible by 3, you have another common factor, which is 3. Then, you can divide the most recent results by 3.3 ÷ 3 = 115 ÷ 3 = 5Since 1 and 5 do not have any common factors, take the two factors that you did identify, 50 and 3, and multiply them together: 50 x 3 = 150. This number, 150, is the greatest common factor.Method: Find All the FactorsIf the numbers are small enough or you know that they have only a few factors, you can list all the factors of each number and compare to determine the largest factor they have in common. One of the related questions links will take you to a page with the complete list of factors for numbers 1 through 100.Example: Find the greatest common factor of 15 and 18.The factors of 15 are 1, 3, 5, and 15.The factors of 18 are 1, 2, 3, 6, 9, and 18.The common factors are 1 and 3, so the greatest common factor is 3.Example: Find the greatest common factor of 26 and 91.The factors of 26 are 1, 2, 13, and 26.The factors of 91 are 1, 7, 13, and 91.The common factors are 1 and 13, so the greatest common factor is 13.Method: Find the Prime FactorsIn situations where you cannot get a good start simply by looking at the numbers, follow the following steps:1. Determine the prime factors of each number. See the related question "How do you find prime factors" for a method on doing this. Also, one of the related questions links will take you to a page with the complete list of prime factors for numbers 1 through 100.2. Determine the prime factors they have in common.3. Multiply all the prime factors they have in common to calculate the greatest common factor. Example: Find the greatest common factor of 5,544 and 37,620.The prime factors of 5,544 are 2, 2, 2, 3, 3, 7, and 11.The prime factors of 37,620 are 2, 2, 3, 3, 5, 11, and 19.The common prime factors are 2, 2, 3, 3, and 11.Therefore, the greatest common factor is 2 x 2 x 3 x 3 x 11 = 396. Example: Find the greatest common factor of 7,888 and 10,002.The prime factors of 7,888 are 2, 2, 2, 2, 17, and 29.The prime factors of 10,002 are 2, 3, and 1667.The common prime factors are a single 2.Therefore, the greatest common factor is 2. Method: Euclidean AlgorithmThis method is more efficient than finding the prime factors when the numbers are large, but teachers might prefer that you gain experience determining the prime factors of numbers. For this method, divide the larger number by the smaller number, then divide the "divisor" from the previous division by the remainder from the previous division, and continue until a number divides evenly. That divisor is the greatest common factor. Example: Find the greatest common factor of 33 and 77.77 ÷ 33 = 2 remainder 1133 ÷ 11 = 3 with no remainderSo, the final divisor, 11, is the greatest common factor. Example: Find the greatest common factor of 27 and 168.168 ÷ 27 = 6 remainder 627 ÷ 6 = 4 remainder 36 ÷ 3 = 2 with no remainderSo, the final divisor, 3, is the greatest common factor.---- Shortcut 1: If one number is a multiple of the other, the smaller number is the greatest common factor, because it is the largest possible factor of itself.Example: Find the greatest common factor of 72 and 288.288 is divisible by 72, therefore 72 is the greatest common factor.Shortcut 2: The greatest common factor of two numbers cannot be larger than the difference between the two numbers. So, you only need to test the numbers that are equal to or less than the difference between those two numbers. Also, the greatest common factor must be a factor of the difference between the two numbers. (This shortcut can help with finding the greatest common factor of three or more numbers. Examples are shown in the related question on finding the greatest common factor of three or more numbers.)Example: Find the greatest common factor of 56 and 64.The difference between 56 and 64 is 64 - 56 = 8. The largest possible common factor is the difference itself. So, check whether 8 divides evenly into both of them.56 ÷ 8 = 764 ÷ 8 = 8Therefore, 8 is the greatest common factor. Example: Find the greatest common factor of 72 and 88.The difference between 88 and 72 is 88 - 72 = 16. Check whether 16 divides evenly into both of them. It does not. But, the greatest common factor must be a factor of 16. The factors of 16 are 1, 2, 4, 8, and 16. So, try the next largest factor, 8, and see if it divides evenly into both of them.72 ÷ 8 = 988 ÷ 8 = 11Therefore, 8 is the greatest common factor.Example: Find the greatest common factor of 1003 and 1180.The difference between 1180 and 1003 is 177. Check whether 177 divides evenly into both of them. It does not. But, the greatest common factor must be a factor of 177. By using the divisibility rule for 3, you know that 3 is a factor of 177, but the divisibility rule indicates that neither 1003 nor 1180 are divisible by 3. 177 ÷ 3 = 59, so check 59 as a factor of both numbers. Note that 3 and 59 are both prime numbers, so they are the only prime factors of 177, so if there is a greatest common factor of 1003 and 1180 other than 1, since we have ruled out 177 and 3, it must be 59.1003 ÷ 59 = 171180 ÷ 59 = 20Therefore, 59 is the greatest common factor. Corollary 1 to Shortcut 2: If the numbers are only one number apart, they are relatively prime and have no common factor other than 1. Example: Find the greatest common factor of 4 and 5.The difference is 1, so the greatest common factor is 1. They are relatively prime.Corollary 2 to Shortcut 2: If the difference between the two numbers is 2 and the numbers are not even numbers, they are relatively prime and have no common factor other than 1. If the difference is 2 and they are both even, the greatest common factor is 2.Example: Find the greatest common factor of 13 and 15.The difference is 2 and the numbers are not even, so the greatest common factor is 1. Example: Find the greatest common factor of 14 and 16.The difference is 2 and the numbers are even, so the greatest common factor is 2.Corollary 3 to Shortcut 2: If the difference between the two numbers is a prime number, either that number is the greatest common factor or 1 is the greatest common factor. Example: Find the greatest common factor of 40 and 69.The difference is 29, which is a prime number. Since 29 does not divide evenly into both 40 and 69, the greatest common factor is 1, which means they are relatively prime. Example: Find the greatest common factor of 91 and 104.The difference is 13, which is a prime number. Since 13 divides evenly into both 91 and 104, the greatest common factor is 13.91 ÷ 13 = 7104 ÷ 13 = 8 Shortcut 3: If one of the numbers is prime, either it is the greatest common factor or the greatest common factor is 1. (Its only factors are 1 and itself, so those are the only possible common factors it could have with another number.)Example: Find the greatest common factor of 83 and 90.83 is a prime number and it is not a factor of 90, so the greatest common factor is 1. Example: Find the greatest common factor of 41 and 246.41 is a prime number and it is a factor of 246, so the greatest common factor is 41.246 ÷ 41 is 6---- Divisibility Rules:To determine the prime factors, it is sometimes helpful to use the divisibility rules.2: The number ends in 0, 2, 4, 6, or 8.Examples: 14, 58, 100, 33363: The sum of the number's digits is divisible by 3.Examples: 78 (7+8=15 which is divisible by 3), 114 (1+1+4=6 which is divisible by 3)5: The number ends in 0 or 5.Examples: 70, 195, 48607: The last digit doubled subtracted from the rest of the number is divisible by 7 or is equal to 0.Examples: 343 (3x2=6; 34-6=28 which is divisible by 7), 875 (5x2=10; 87-10=77 which is divisible by 7)11: Start with the left-most digit, subtract the next one, add the next one, subtract the next one, etc., and the final result is divisible by 11 or is equal to 0.Examples: 165 (1-6+5=0), 308 (3-0+8=11 which is divisible by 11), 1078 (1-0+7-8=0)Prime Numbers: Prime factors are prime numbers. The first 25 prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97.
What is the GCF of 6 and 40?
Factors of 6 are 1, 2, 3 and 6.Factors of 40 are 1, 2, 4, 5, 8, 10, 20 and 40.Common factors are 1 and 2. Therefore, the greatest common factors(gcf) is 2.Alternate method:The method used above is not useful for finding GCF of larger numbers.However, the method of prime factorization is very useful and simple for finding GCF.Prime factorization of 6 = 2x3Prime factorization of 40 = 2x2x2x5It is clear from the factorization of both numbers that 2 is the GCF.
What is the trick to finding the greatest common factor of three or more numbers?
The standard ways of determining the greatest common factor of three or more numbers is* to compare all their factors and choose the largest one that is common to all, or * to compare their prime factors and multiply together all the ones that are common to all, or * to determine the greatest common factor two numbers at a time.However, you can also look at the difference between the numbers being compared. The greatest common factor cannot be greater than the smallest difference between the numbers. Also, the greatest common factor must be a factor of the difference between the numbers.Example: Find the greatest common factor of 8, 10, and 14.The difference between 8 and 10 is 2, which means the greatest common factor cannot be greater than 2. (The difference between 10 and 14 is 4 and the difference between 8 and 14 is 6, both of which are divisible by 2, so 2 remains a possible greatest common factor.) So, check whether 2 evenly divides 8, 10, and 14. It does, so 2 is the greatest common factor.Example: Find the greatest common factor of 84, 91, and 105.The difference between 84 and 91 is 7, which means the greatest common factor cannot be greater than 7. (The difference between 91 and 105 is 14 and the difference between 105 and 84 is 21, both of which are divisible by 7, so 7 remains a possible greatest common factor.) So, check whether 7 evenly divides 84, 91, and 105. It does, so 7 is the greatest common factor. Here are the factors for those numbers so you can see that it is correct:The factors of 84 are 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, and 84.The factors of 91 are 1, 7, 13, and 91.The factors of 105 are 1, 3, 5, 7, 15, 21, 35, and 105.More Complex Example: Find the greatest common factor of 42, 54, and 66.The difference between 42 and 54 is 12, which is also the same difference between 54 and 66, so the greatest common factor cannot be greater than 12. So, check whether 12 evenly divides 42, 54, and 66. It does not, so try the largest factor of 12 that is less than 12, which is 6. Check whether 6 divides evenly 42, 54, and 66. It does, so 6 is the greatest common factor. Here are the factors for those numbers so you can see that it is correct:The factors of 42 are 1, 2, 3, 6, 7, 14, 21, and 42.The factors of 54 are 1, 2, 3, 6, 9, 18, 27, and 54.The factors of 66 are 1, 2, 3, 6, 11, 22, 33, and 66.More Complex Example: Find the greatest common factor of 36, 42, and 76.The difference between 36 and 42 is 8. The difference between 42 and 76 is 34. Since the greatest common factor must be a factor of the difference, we can examine these smaller numbers, 8 and 34, to see if they have a factor in common. The only factor they have in common (excluding 1) is 2. Since 2 evenly divides 36, 42, and 76, it is the greatest common factor. Here are the factors for those numbers so you can see that it is correct:The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, and 36.The factors of 42 are 1, 2, 3, 6, 7, 14, 21, and 42.The factors of 76 are 1, 2, 4, 19, 38, and 76.Four Numbers Example: Find the greatest common factor of 27, 39, 54, and 60.The difference between 27 and 39 is 12. The difference between 39 and 54 is 15. The difference between 54 and 60 is 6. Since the greatest common factor must be a factor of the difference, we can examine these smaller numbers, 12, 15, and 6, to see if they have a factor in common. The only factor they have in common (excluding 1) is 3. Since 3 evenly divides 27, 39, 54, and 60, it is the greatest common factor. Here are the factors for those numbers so you can see that it is correct:The factors of 27 are 1, 3, 9, and 27.The factors of 39 are 1, 3, 13, and 39.The factors of 54 are 1, 2, 3, 6, 9, 18, 27, and 54.The factors of 60 are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60.The same way as with two. You can list the factors and find the common ones or compare their prime factorizations.
What is criss angel's greatest trick?
Levitating and walking on water are 2 of his greatest tricks.
Is there a trick to finding the fifth item in collections on Cafe World?
No..
What is the trick to finding the lowest common multiple?
Example: 30 and 42 Factor them. 2 x 3 x 5 = 30 2 x 3 x 7 = 42 Combine the factors, eliminating duplicates. 2 x 3 x 5 x 7 = 210, the LCM
What is 25 over 27 in simplest form?
Trick question - 25/27 is already in simplest form. Divisors of 25: 1,5,25 Divisors of 27: 1,3,9,27 Since the greatest common divisor is 1, you can not simplify any further.
What is the greatest magic trick in the world?
life and death game
