One more, one less, ten more, ten less
Maths · Key Stage 1 · The School
One more, one less
One more than a number is the next number. One more than 15 is 16. One less is the number just before it. One less than 15 is 14. Count up. Count down. Find the neighbours of a number.
Ten more, ten less: the ones digit sits still
Ten more than 23 is 33. Only the tens digit moved, from 2 to 3. The ones digit is still 3. Ten less than 47 is 37. The tens digit drops from 4 to 3. The 7 does not move. Check the ones digit. If it moved, the answer is wrong.
When one more crosses into a new ten
One more than 29 is not "2-10". It is 30. The ones digit rolls from 9 to 0. The tens digit ticks up, from 2 to 3. This only happens right at the edge of a ten. Ten more and ten less never do this. The ones digit never moves for those.
A shortcut you can use
You know 34. Ten more is 44. Ten less is 24. No counting needed. 34 + 10 becomes a fact you already know, not a sum to work out. Try 61. Ten more is 71. Ten less is 51. Two quick facts, no counting, every time.
One number, four moves
Take 56. One more is 57. One less is 55. Ten more is 66. Ten less is 46. Four answers from one number. Each move changes just one thing. Say which move you are making before you answer. That stops you mixing them up.