Addition

Whether you add up what your shopping costs or how many points you have collected in a game: you add all the time, often without noticing. Here we turn that gut feeling into a reliable skill, so adding never gets in your way again.

What does adding mean?

Adding means counting together. If you have 3 apples and get 4 more, you have 7: we write 3 + 4 = 7. The numbers you add are called addends, the result is called the sum. On the number line you can picture adding as jumping: you start at the first number and jump ahead by the second.

Order doesn't matter

3 + 4 gives the same as 4 + 3. That's always true, for all numbers. It's called the commutative law. It's more useful than it sounds: you may always start with whichever number makes it easier. For 2 + 39, better to start at 39 and jump 2 ahead.

The tens trick

Big jumps become easy when you anchor them at round numbers. For 8 + 5, jump 2 first (to reach 10), then 3 more: that's 13. With bigger numbers, split by place value: 46 + 38 is 40 + 30 and 6 + 8, together 70 + 14 = 84. That's exactly what you'll practise in the exercises.