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How is multiplying fractions by a whole number is different from adding adding and subtracting fractions with like denominators?

Updated: 4/28/2022

Dariusgotemallwalker

Lvl 1
9y ago

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.

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9y ago

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Q: How is multiplying fractions by a whole number is different from adding adding and subtracting fractions with like denominators?
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Can you multiply fractions that have a different demonminator?

Yes. When multiplying and dividing fractions your denominators do not have to be the same. The denominators only haveto be the same if you are subtracting or adding them.

How do you subtract improper fractions with different denominators?

It's the same thing as adding or subtracting normal fractions - just make sure both fractions have the same denominators (by either multiplying the denominators or simplifying the fraction - whichever the question needs).

Are the steps for like and unlike denominators the same or different?

It depends what you are doing with the fractions. If you are multiplying or dividing fraction, the denominators do not need to be the same and the calculation can be carried out immediately. If you are adding or subtracting fractions, the denominators must be the same; if you have different denominators, the fractions must first be changed into equivalent fractions with the same denominator. When the denominators are the same (or have been made the same as equivalent fractions from being different) the calculation can be carried out.

When adding or subtracting fractions their denominators must be the same

Why does the equivalent fraction make adding and subtracting fractions easier?

You cannot add or subtract fractions with different denominators. If the denominators are different then you need to work with equivalent fractions.

What is the process of subtracting fractions?

If the denominators are the same, subtract the numerators. If the denominators are different, convert them to equivalent fractions with a common denominator and subtract the numerators.

When will you need to find the multiples and factors?

When adding or subtracting fractions with different denominators and when reducing fractions to their lowest terms

Do you have to change the denominators when multiplying 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.

What is the definition of adding and subtracting fractions with unlike denominators?

What is the definition of Adding and Subtracting Like Fractions

how to rename fractions using LCM?

When adding or subtracting fractions with different denominators their lowest common denominator must be found first by using the LCM of their denominators

Why do you have to have a common denominator?

A common denominator is needed when adding or subtracting fractions of different denominators.

Why are two fractions converted into like fractions?

Because you can't add or subtract fractions that have different denominators. Making them like fractions, by multiplying so the denominators are the same, you can add and/or subtract them.