Number Trios

If you know an addition fact, you can work out a related subtraction fact. Learning number trios are very useful.

The numbers 11, 4, 7 can be made into these four sums by just swapping the two lower numbers.

4 + 7 = 11               11 - 4 = 7
7 + 4 = 11               11 - 7 = 4

This can be done with many other numbers.

Use your flashcards to play a game. Pick three numbers, two of which add up to the third one. Then try and create four sums using only the plus, minus and equals.

Adding multiple-digit numbers