Addition and Subtraction Facts to 20 (1)

Look at this number square, which shows all the bonds you should know by heart up to 20.

 

 

Example 1

Add  6 + 9 

 

Answer

You should know this by heart, but the number square shows that it is 15.

 

 

Example 2

Subtract  15 - 9 

 

Answer

You should know this by heart, but the number square shows that it is 6.

When you subtract, the starting number is inside the square.

 

 

Example 3

Add  12 + 5

 

Answer

You should know that   2 + 5 = 7,

so 12 + 5 = 17

 

Example 4

Subtract 16 - 12

 

Answer

You should know that   6 - 2 = 4,

so 16 - 12 = 4 as well.