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Calculate 1/2 + 1/3 × 3/4

Step by step, with the reason for every step · Fractions · Foundations

Step by step

The question

Question: work out 1/2 + 1/3 × 3/4.

12 + 13 × 34

1 Times and divide

Times comes before plus.

Order: ( ) → x² √ → × ÷ → + −

Before we multiply, we make the numbers smaller.

3 on top and 3 at the bottom both divide by 3.

A top and a bottom divided by the same number: the answer stays the same.

3 and 3: ÷ 3 → 1 and 1

So we multiply smaller numbers.

= 12 + 11 × 14

To multiply fractions, we do top times top, and bottom times bottom.

= 12 + 1 × 11 × 4

1 times 1 is 1.

1 times 4 is 4.

= 12 + 14

2 Plus and minus

The bottom numbers are 2 and 4.

They are different, so we can't add the tops yet.

We count up in 2s and in 4s.

4 is the first number in both lists.

So 4 will be the new bottom.

In 2s: 2, 4
In 4s: 4

2 times 2 is 4.

So 1/2 gets times 2/2.

1/4 already has 4 at the bottom.

2 × 2 = 4

We multiply the top and the bottom by the same number.

= 12 × 22 + 14

2/2 is 1.

Times 1 does not change the size.

So the fraction stays the same, only the bottom changes.

22 = 1

Top times top.

Bottom times bottom.

= 1 × 22 × 2 + 14

1 times 2 is 2.

2 times 2 is 4.

Now both have 4 at the bottom.

= 24 + 14

The bottoms are the same, so the pieces are the same size.

We add the tops.

The bottom stays 4, because the size of the pieces does not change.

= 2 + 14

2 plus 1 is 3.

= 34

Can we make it simpler?

No number goes into both 3 and 4, except 1.

So it stays like this.

simplest ✓

So the answer is 3/4.

Let's look back.

First: times and divide.

Last: plus and minus.

Answer
= 34

Your turn

Try this one yourself, then check:

12 + 14 × 45
Show the answer
710

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