The strategy
How it works
Start at the smaller number.
Jump to a nearby ten, then to the larger number.
Add the jump sizes to get the difference.
See it in action
Worked examples
Example 152 − 48
- 48 to 50 is 2.
- 50 to 52 is 2.
- 2 + 2 = 4.
Answer: 4
Example 283 − 67
- 67 to 70 is 3.
- 70 to 80 is 10; 80 to 83 is 3.
- 3 + 10 + 3 = 16.
Answer: 16
A quick heads-up
Common mistakes to avoid
- Starting from the larger number and counting up again; always begin at the number being subtracted.
- Forgetting one of the jumps; mark each friendly number you pass.
Your turn
Check your understanding
Choose an answer to see instant feedback and a short explanation. You can take the quiz again any time.
Question 1 of 3
How far is it from 76 up to 80?
76 + 4 = 80, so that jump is 4.
What is 61 − 58?
Count up: 58 to 60 is 2, then 60 to 61 is 1. Total gap: 3.
What is 92 − 78?
78 to 80 is 2, to 90 is 10, and to 92 is 2. The jumps total 14.
Keep the momentum
Try a few practice problems
Choose a comfortable range and work through a short round with the free mental math trainer.