Add And Subtract Fractions

Before viewing this page, it would be helpful to learn how to calculate Equivalent Fractions.

Mechanics working on some car engines use common fractions.

Many drill bits, sockets and Allen keys are in Imperial sizes such as 12 inch, 14 inch, 18 inch and so on.

Steps to add and subtract common fractions are:



Example One - Adding Allen Keys

Allen Keys

Allen keys are used to measure gaps in car engines. Into a gap, Allen keys with thicknesses of 12 inch and 14 inch can fit. What is the width of the gap?

Answer:
12 + 14
= 24 + 14 (Steps 1 and 2)
= 34 (Step 3)


Example Two - Adding Allen Keys

What is the width of a gap into which Allen keys with thicknesses of 38 inch and 116 inch can fit?

Answer:
38 + 116
= 616 + 116 (Steps 1 and 2)
= 716 (Step 3)


Example Three - Adding Pizza Slices

3 quarters diagram 2 thirds diagram

What is the total of 34 pizza and 23 pizza?

Answer:
34 + 23
= 912 + 812 (Steps 1 and 2)
= 1712 (Step 3)
= 1 512 (Step 4)


Example Four - Subtracting Pizza Slices

There is 34 of a pizza. If I eat 23 pizza, how much is left?

Answer:
3423
= 912812 (Steps 1 and 2)
= 112 (Step 3)

Questions

Q1. 12 + 13
Q2. 34 + 13
Q3. 78 + 34
Q4. 5638

Answers
A1. 56
A2. 1 112
A3. 1 58
A4. 1124

Example Five - Adding Mixed Numbers

1 3/4 diagram 1 2/3 diagram

Add 1 34 and 1 23.

Answer:
Change these mixed numbers to improper fractions first.
1 34 + 1 23
= 74 + 53
= 2112 + 2012
= 4112
= 3 712

Questions

Q1. 2 18 + 3 34
Q2. 3 14 – 1 15

Answers
A1. 5 78
A2. 2 120

Maths Fun

Bob loves to count. One day, his teacher put a pile of pencils on Bob's desk. Bob began to count the pencils. He told his teacher the following facts about the pencils:

How many pencils are there?