Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 59 · 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. 1.752 − 229 =
2. 2.813 − 698 =
3. 3.730 − 598 =
4. 4.789 − 129 =
5. 5.536 − 298 =
6. 6.249 − 199 =
7. 7.430 − 198 =
8. 8.615 − 399 =
9. 9.930 − 438 =
10. 10.654 − 598 =
11. 11.920 − 799 =
12. 12.642 − 597 =
13. 13.896 − 447 =
14. 14.859 − 259 =
15. 15.629 − 549 =
16. 16.601 − 187 =
17. 17.770 − 627 =
18. 18.671 − 599 =
19. 19.788 − 699 =
20. 20.976 − 199 =
21. 21.553 − 198 =
22. 22.549 − 187 =
23. 23.774 − 698 =
24. 24.882 − 617 =
25. 25.747 − 397 =
26. 26.477 − 358 =
27. 27.716 − 597 =
28. 28.472 − 417 =
29. 29.379 − 197 =
30. 30.852 − 538 =
31. 31.890 − 798 =
32. 32.947 − 598 =
33. 33.616 − 597 =
34. 34.796 − 569 =
35. 35.877 − 178 =
36. 36.651 − 397 =
37. 37.952 − 197 =
38. 38.965 − 197 =
39. 39.414 − 398 =
40. 40.814 − 699 =

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