Adding and taking away within 18 · Usually met around P1
The equals sign means “the same as”
Work out each side; true only if they match.
How to do it
Method
Work out each side; true only if they match
4 + 3 = 5 + 2: both sides are 7
Another way
A balance
7 on the left, 7 on the right: it balances
In full
The equals sign “=” doesn't mean “the answer is”; it means “both sides are the same”. Work out the left side and the right side on their own: only if they match is it true. 4 + 3 = 5 + 2: the left is 7 and the right is 7 too, so it is true. 7 = 8 − 1 is true as well, since 8 − 1 is 7: a single number can sit on the left. Or picture a balance: it only balances when both sides weigh the same; if one side is short, add to that side.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
8 = □ − 8
Show the answer and working
Answer: 16
A single number can sit on the left: □ take away 8 must leave 8, so □ is 8 + 8 = 16.
Example 2
9 + 7 = 8 + 7
True or false?
Show the answer and working
Answer: False
The left is 9 + 7 = 16, the right 8 + 7 = 15. It is only true if both sides match.
Example 3
7 + 5 = 3 + □ = □ + 7
Fill in each box
Show the answer and working
Answer: 9，5
Each equals sign means the sides match, so all three parts are 12: 3 + 9 = 12 and 5 + 7 = 12.
Practise it in the game →Adding and taking away within 18 · Free to start, unlimited questions, no download