Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 28 · 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. 1.747 − 307 =
2. 2.630 − 198 =
3. 3.884 − 268 =
4. 4.647 − 499 =
5. 5.719 − 397 =
6. 6.794 − 159 =
7. 7.601 − 229 =
8. 8.751 − 277 =
9. 9.324 − 129 =
10. 10.733 − 699 =
11. 11.708 − 638 =
12. 12.869 − 129 =
13. 13.724 − 618 =
14. 14.936 − 527 =
15. 15.884 − 499 =
16. 16.922 − 307 =
17. 17.629 − 148 =
18. 18.457 − 299 =
19. 19.434 − 197 =
20. 20.546 − 519 =
21. 21.594 − 498 =
22. 22.928 − 797 =
23. 23.394 − 297 =
24. 24.585 − 197 =
25. 25.746 − 238 =
26. 26.791 − 699 =
27. 27.515 − 299 =
28. 28.839 − 497 =
29. 29.646 − 499 =
30. 30.903 − 599 =
31. 31.752 − 398 =
32. 32.755 − 687 =
33. 33.854 − 798 =
34. 34.584 − 567 =
35. 35.872 − 697 =
36. 36.554 − 328 =
37. 37.984 − 799 =
38. 38.822 − 299 =
39. 39.601 − 469 =
40. 40.557 − 417 =

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