Using whole numbers, find pairs of addends that add to 11. e.g. 3 + 8 = 11

• How many pairs altogether add to 11?
• If the sum is 12, how many pairs of addends can you find?
• What if the sum is 13? How many pairs of addends?
• Can you predict how many pairs there would be if the total is 25, 99, 120 or 1000?

Make a table with your information to see if you can find and predict the patterns.

Find a rule for the number of addition pairs when the sum is ODD and the sum is EVEN.

Answer

The idea for this investigation came from The Maths' Connection published by Family Maths Trust