Clever ways to add and take away in your head, drawn as jumps on a number line.
22 = 20 + 2
From 84, jump −20. Where do you land?
Split it
47 + 25: jump 20, then 5.
Round and adjust
46 + 29: jump 30, then back 1.
Near doubles
16 + 17: double 16, then 1 more.
Ways of working out a sum in your head by breaking it into easier steps. Instead of lining up columns, you split numbers, round them or use facts you already know, like doubles.
When a number is close to a ten, use the ten instead and fix it afterwards. 46 + 29 is 46 + 30 = 76, then take 1 away because 29 is 1 less than 30: 75. For taking away it's the other way: 63 − 19 is 63 − 20 = 43, then add 1 back: 44.
A number line shows each step as a jump, so children can see how far they've gone and where they've landed. Writing the jumps down also helps them keep track without doing the whole sum in their head at once.
Children start with near doubles and adding tens at about 6 to 7, split two-digit numbers at about 7 to 8, and use rounding and adjusting at about 8 to 9.