The factors of the two numbers are :- 51 : 1, 3, 17 and 51 21 : 1, 3, 7 and 21. Ignoring the trivial factor of 1, the only common factor and therefore the greatest common factor is 3.
The highest common factor of the given numbers is 1
21 and 28 have 7 as a factor.
It depends on what the numbers are. For example, if the prime numbers you were talking about were 3 and 7, the least common multiple would be 21. If your numbers were 2 and 3, it would be 6.
The only common factor of all three numbers is 3. (The numbers 21 and 63 share all of the factors of 21 : 1, 3, 7, and 21.)
3x7=21 3 and 7 are prime numbers, so 3x7 is the factor tree of the number 21.
3 and 7
3 and 7
21
21 3,7
21 3,7
Factor tree:126|63 and 2|21 and 32 x 3 x 21 = 126
21/ \7 3
21 3,7
First, find two numbers that when multiplied together equal 189. I can tell by looking at the number that it is divisible by 9. Any number whose digits add up to a number divisible by 9 is also divisible by 9. 1 + 8 + 9 = 18, which is divisible by 9. 189 ÷ 9 is 21. So, the top of our factor tree is: 189 9 x 21 Now, determine two pairs of numbers that when multiplied together, one pair will equal 9 and the other pair will equal 21. 9 = 3 x 3 and 21 = 7 x 3. So, now our factor tree is: 189 9 x 21 (3x3) x (7x3) You would continue doing this until you no more numbers can be factored. Since 3 and 7 are prime numbers, the factor tree is finished. The factor tree shows that the prime factorization of 189 is 3 x 3 x 3 x 7 or 33 x 7.
21 is equal to 3 times 7.
21 3,7