Calculate -0.6 + 1.5 Easy
The question
Question: work out −0.6 + 1.5.
−0.6 + 1.5
1 Add
Start at −0.6.
Go up 1.5.
We land on 0.9.
= 0.9
So the answer is 0.9.
Answer
= 0.9
Negative fractions and decimals
+ − × ÷ with the sign rules · Foundations · 23 problems, easy to harder
How we do it
- Make one fraction
- Make the bottoms the same
- Add the tops
- Write as a mixed number
The steps for Calculate -3 1/2 + 1 1/4. Every solution names its steps, so you always know what comes next.
Worked examples
Calculate -3/4 + 1/2 Medium
The question
Question: work out −3/4 + 1/2.
−34 + 12
1 Make the bottoms the same
The bottom numbers are 4 and 2.
They are different, so we can't add the tops yet.
We count up in 4s and in 2s.
4 is the first number in both lists.
So 4 will be the new bottom.
In 4s: 4
In 2s: 2, 4
−3/4 already has 4 at the bottom.
2 times 2 is 4.
So 1/2 gets times 2/2.
2 × 2 = 4
We multiply the top and the bottom by the same number.
= −34 + 12 × 22
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.
= −34 + 1 × 22 × 2
1 times 2 is 2.
2 times 2 is 4.
Now both have 4 at the bottom.
= −34 + 24
2 Add the tops
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.
= −3 + 24
−3 plus 2 is −1.
= −14
Can we make it simpler?
No number goes into both 1 and 4, except 1.
So it stays like this.
simplest ✓
So the answer is −1/4.
Let's look back.
First: make the bottoms the same.
Last: add the tops.
Answer
= −14
Calculate -3 1/2 + 1 1/4 Harder
The question
Question: work out −3 and 1/2 + 1 and 1/4.
−312 + 114
1 Make one fraction
3 and 1/2 is a mixed number.
Each whole one is 2/2.
So we do 3 times 2, plus 1.
The bottom stays 2.
= −3 × 2 + 12 + 114
3 times 2 plus 1 is 7.
So it is 7/2.
= −72 + 114
1 and 1/4 is a mixed number.
Each whole one is 4/4.
So we do 1 times 4, plus 1.
The bottom stays 4.
= −72 + 1 × 4 + 14
1 times 4 plus 1 is 5.
So it is 5/4.
= −72 + 54
2 Make the bottoms the same
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 −7/2 gets times 2/2.
5/4 already has 4 at the bottom.
2 × 2 = 4
We multiply the top and the bottom by the same number.
= −72 × 22 + 54
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.
= −7 × 22 × 2 + 54
7 times 2 is 14.
2 times 2 is 4.
Now both have 4 at the bottom.
= −144 + 54
3 Add the tops
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.
= −14 + 54
−14 plus 5 is −9.
= −94
4 Write as a mixed number
9 divided by 4 is 2, with 1 left over.
So it is 2 and 1/4.
= −214
So the answer is −2 and 1/4.
Let's look back.
First: make one fraction.
Then: make the bottoms the same.
Then: add the tops.
Last: write as a mixed number.
Answer
= −214
Practice
Try each one, then open the answer. Stuck? Open the problem to watch every step.
Easy
- -0.6 + 1.5
Answer
= 0.9 - -3.2 - 1.5
Answer
= −4.7 - -2.5 × 4
Answer
= −10 - -1.5 × -0.4
Answer
= 0.6 - 2.4 ÷ -0.6
Answer
= −4 - -4.8 ÷ -1.2
Answer
= 4 - -1/4 + 3/4
Answer
= 12 - -5/8 - 1/8
Answer
= −34 - -2/3 × 3/5
Answer
= −25
Medium
- -3/4 + 1/2
Answer
= −14 - -1/2 - 3/4
Answer
= −54 - 1/4 - 5/6
Answer
= −712 - -2/3 × -3/4
Answer
= 12 - -1/2 ÷ 3/4
Answer
= −23 - -7.5 + 2.25
Answer
= −5.25 - -0.3 × -0.2
Answer
= 0.06 - -6.3 ÷ 0.9
Answer
= −7 - -3/5 ÷ -9/10
Answer
= 23
Harder
- -3 1/2 + 1 1/4
Answer
= −214 - -2 1/3 - 1 1/2
Answer
= −356 - -(2/3) × 9/10
Answer
= −35 - -1.25 × 0.8
Answer
= −1 - -5/6 + -1/4
Answer
= −1312