Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 460 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.765 − 659 =
2. 2.955 − 599 =
3. 3.626 − 197 =
4. 4.764 − 297 =
5. 5.652 − 519 =
6. 6.909 − 399 =
7. 7.892 − 499 =
8. 8.908 − 598 =
9. 9.912 − 597 =
10. 10.761 − 698 =
11. 11.363 − 199 =
12. 12.892 − 287 =
13. 13.720 − 587 =
14. 14.691 − 469 =
15. 15.956 − 799 =
16. 16.846 − 297 =
17. 17.710 − 629 =
18. 18.548 − 169 =
19. 19.611 − 199 =
20. 20.583 − 399 =
21. 21.419 − 298 =
22. 22.372 − 198 =
23. 23.731 − 699 =
24. 24.757 − 398 =
25. 25.796 − 299 =
26. 26.518 − 497 =
27. 27.875 − 418 =
28. 28.735 − 298 =
29. 29.873 − 497 =
30. 30.390 − 227 =
31. 31.837 − 799 =
32. 32.859 − 799 =
33. 33.575 − 298 =
34. 34.434 − 299 =
35. 35.693 − 538 =
36. 36.461 − 197 =
37. 37.462 − 399 =
38. 38.802 − 297 =
39. 39.823 − 799 =
40. 40.495 − 377 =

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