Best Answer

A common denominator.

Steps to take for addition/subtraction of fractions.

#1 ; Bring to improper(top heavy) fractions.

#2 ; Bring to a common denominator by making equivalent fractions.

#3 ; Add/subtract the numerators(top number).

#4 ; Bring back to a mixed number by dividing the denominator into the numerator.

An example.

5 2/3 +/- 7 7/8

#1 ; 17/3 +/- 63/8

#2 ; NB 24 is the common denominator (3 x 8).

136/24 +/- 189/8

#3 ; 325/24 & 53/24

#4 ; 13 13/24 & 2 5/24 The answer(s). !!!!

NB For multiplication of fractions.

Steps to take

#1 ; Bring to improper(top heavy) fractions.

#2 ; Cancel down as appropriate

#3 ; Multiply the numerators together, and then multiply the denominators together.

#4 ; . Brind back to a mixed fraction.

Using the same fraction as an example

5 2/3 X 7 7/8

17/3 X 63/8

Cancel down by '3'

17/1 X 21/8 =

357/8

44 5/8 The answer !!!!

For division of fractions , the steps to take are the same except for one very important step, which we'll call it #1a.

#1 ; Bring to improper(top heavy) fractions.

#1a ; VERY IMPORTANT ' ; change the sign to multiply and invert (turn over) the right hand fraction.

#2 ; Cancel down as appropriate

#3 ; Multiply the numerators together, and then multiply the denominators together.

#4 ; . Brind back to a mixed fraction.

Using the same numbers again/

5 2/3 Divide 7 7/8

Thus

17/3 divide 63/8

IMPORTANT STEP

17/3 X 8/63 NOTE what has happened.

We now cancel down . However, these numbers do not cancel down , so we apply #3 for multiplication.

136/189

#4 for multiplication ; these numbers do not cancel down , and so 136/189 remains as the fractional answer.

Hope that helps!!!!!

Q: When adding or subtracting fractions you must first make sure you find a?

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In order to find the LCD when adding or subtracting fractions

Same as for adding: If the denominators are not equal, you must first find a common denominator, then convert both fractions to that common denominator.

If their denominators are different then find their lowest common denominator by means of their lowest common multiple remembering to adjust their numerators accordingly before adding or subtracting.

Subtracting fractions is similar to adding fractions. If the fractions have the same denominator, you subtract the numerators. If the fractions have different denominators, you have to convert to a common denominator first.Subtracting fractions is similar to adding fractions. If the fractions have the same denominator, you subtract the numerators. If the fractions have different denominators, you have to convert to a common denominator first.Subtracting fractions is similar to adding fractions. If the fractions have the same denominator, you subtract the numerators. If the fractions have different denominators, you have to convert to a common denominator first.Subtracting fractions is similar to adding fractions. If the fractions have the same denominator, you subtract the numerators. If the fractions have different denominators, you have to convert to a common denominator first.

3/83/4 - 3/8 = 6/8 - 3/8 = 3/8Always find the common denominator first when adding or subtracting fractions.

Related questions

first u find a common denominator

When adding or subtracting fractions first make sure that the denominators are the same if they aren't then find the lowest common denominator and alter the fractions accordingly

Because to add or subtract two fractions you first have to find equivalent fractions for both which have the same denominator.

Find a common denamonator.

In order to find the LCD when adding or subtracting fractions

Same as adding, multiplying, and dividing.

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

Finding the LCM helps in the process of adding and subtracting unlike fractions.

When you are adding or subtracting unlike fractions.

Same as for adding: If the denominators are not equal, you must first find a common denominator, then convert both fractions to that common denominator.

If their denominators are different then find their lowest common denominator by means of their lowest common multiple remembering to adjust their numerators accordingly before adding or subtracting.

This can be especially helpful if you are adding or subtracting fractions, so the bottom number on both fractions will be the same