Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 522 · 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. 1.249 − 187 =
2. 2.964 − 418 =
3. 3.843 − 798 =
4. 4.892 − 298 =
5. 5.687 − 388 =
6. 6.954 − 497 =
7. 7.829 − 297 =
8. 8.877 − 689 =
9. 9.761 − 199 =
10. 10.519 − 298 =
11. 11.624 − 498 =
12. 12.785 − 418 =
13. 13.844 − 608 =
14. 14.409 − 197 =
15. 15.703 − 679 =
16. 16.984 − 647 =
17. 17.575 − 398 =
18. 18.735 − 378 =
19. 19.329 − 167 =
20. 20.512 − 499 =
21. 21.795 − 339 =
22. 22.702 − 147 =
23. 23.571 − 499 =
24. 24.771 − 297 =
25. 25.618 − 597 =
26. 26.558 − 399 =
27. 27.948 − 798 =
28. 28.694 − 619 =
29. 29.507 − 167 =
30. 30.571 − 297 =
31. 31.751 − 698 =
32. 32.321 − 239 =
33. 33.406 − 299 =
34. 34.738 − 698 =
35. 35.929 − 597 =
36. 36.736 − 508 =
37. 37.963 − 227 =
38. 38.982 − 659 =
39. 39.642 − 368 =
40. 40.956 − 489 =

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