Q: When adding fractions with the same denominator why do you only add numerators?

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When adding like fractions, only the numerators are added.

No only when adding or subtracting fractions a common denominator is needed

Adding and subtracting fractions can ONLY be done if the denominators are the same; then the calculation is done by adding or subtracting the numerators. Multiplying (and dividing) fractions does not require the denominators to be the same. To divide by a fraction the divisor is inverted (the original numerator becomes the new denominator and the original denominator becomes the new numerator) and then the fractions are multiplied. Multiplying fractions is achieved by multiplying the numerators together AND multiplying the denominators together. A whole number is the same as a fraction with the whole number as the numerator and a denominator of 1, so when multiplying by a whole number the denominator is multiplied by 1 (leaving it the same) and the is multiplication is effectively just multiplying the numerator by the whole number.

Only fractions with the same denominator can be added directly. Addition of such fractions can be achieved by adding their numerators to form the numerator of the sum, with the common denominator of the added fractions constituting the denominator of the sum. In this instance, 2/3 = 6/9, and 4/9 + 6/9 = 10/9.

It stays the same. Only the numerators change.

No, You only need a common denominator when adding or subtracting fractions.

No. To multiple fractions multiple the numerators together and multiply the denominators together and simplify (by dividing both numerator and denominator of the result by common factors until the only common factor is 1). The denominators only need to be the same when adding or subtracting fractions.

Unless you are using a calculator that adds them for you, it is much harder to add fractions with uncommon denominators. Having the same denominator allows you to only have to add the numerators for your answer.

No, you only need a common denominator when adding or subtracting fractions.

Fractions can only be added or subtracted if the denominators are the same. If the denominators are different, then the fractions need to be made into equivalent fractions with the same denominator. The new denominator can be found simply by multiplying the denominators together, but this can lead to some large fractions with which to work. A better new denominator is the lowest common multiple of (all the) denominators. (Once the new denominator is found, the fractions' new numerators are found by multiplying their current numerator by the new denominator divided by their current denominator to make their equivalent fractions with the new denominator.) Once all the fractions are converted into equivalent fractions with the new denominator then the fractions can be added or subtracted, with the result being simplified (if possible).

No. Only if you're adding or subtracting and then only if the denominators are different.

The instructions are quite simple, but this is for similar denominators: 1. Line them up. 2. Add the numerators. 3. Put your sum over the same denominator as the other fractions. 4. *ONLY IF THE NUMERATOR IS LARGER THEN THE DENOMINATOR* Turn the improper fraction into a mixed number. However, if the problem states it wants it as an improper fraction, which normally it won't, leave it as it is.

You can add or subtract fractions only if they are "like" fractions, that is, only if they have the same denominator - unless you know your fractions really well.

find the lowest common denominator so both have the same denominator, then subtract the numerators only leaving the denominator the same For example 1/2 - 1/4 2/4-1/4 = 1/4

You can only add like to like. There is no mechanism for adding different types of fraction.

You add or subtract only the numerators

No but the denominators must be the same and you just add the numerators. If the denominators are different and you have to find which is greater you have to find a denominator that both numbers can multiply into. For example, 5/6 and 3/12 will be our fractions. 6 times to equals 12. Since 12 is the other denominator 3/12 stays the same. Thats the only time you can change the denominator.

Want to be sure I understand~you are adding the 3 fractions? 1/3 + 3/4 + 3/5 = x [NOTE: A bit of info when adding fractions with different denominators (lower number)] -Find the Least Common Denominator (LCD) of all the fractions you are working with. -Rename the fractions to have the LCD. -Add the fractions to have the LCD -Add the numerators (top number) of the fractions once the denominators are the same -Simplify the fraction ~Determine the Greatest Common Factor (GCF) of 3 and 4 and 5 which is 1 ~Multiply the denominators and divide by the GCF 3 x 4 x 5 = 60, then 60 ÷ 1 = 60 ~Rename the fractions to use the Least Common Denominator [LCD] (remembering you multiply both the numerator and denominator by the LCD) 1/3= 20/60, 3/4 = 45/60, 3/5 = 36/60 ~Now you can add the fractions together, remembering that when adding fractions they have to have same common denominator which you are getting with the above actions, only adding the numerators together. ~Result of your math problem 20/60 + 45/60 + 36/60 = 20 + 45 + 36 /60 = 101/60 (20+45+36 over {fraction line showing numerators adding together with 60 the denominator under the 3 numerators added together} under 60) = 101/60 {explained because cannot put underline properly like it would normally look} ~Simplify the fraction. Notice the numerator is more than the denominator. Denominator divided into the higher numerator - how many times does 60 go into 101 in a whole number = 1 with 41 left over or 1 remainder 41 101/60 = 1 41/60 So the three fractions added together equals 1 41/60 (41/60 cannot be reduced or simplified)

There is only one way - make then into equivalent fractions with the same denominator and then add the numerators and simplify if possible. However, there are infinitely many equivalent fractions that can be used - all multiples of the lowest common multiple of 3 and 6 (which is 6) can be used as the denominator for the equivalent fractions.

We can only add or subtract fractions if they have the same denominators

Ok. First you make sure the denominator (bottom number) is the same on all the fractions. The easiest way to do this is to multiply the denominators together, then multiply each numerator by the opposite fractions denominator. This is the easiest way to do this, you will simplify later. ONLY DO THIS IF THE DENOMINATORS ARE DIFFERENT. If they are the same just add the numerators together to get your fraction. Then simplify.

Numerator, Denominator or Denominator, Numerator.

like, common denominator

Numerators

Only in improper fractions where the numerator is a multiple of the denominator.