Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 687 · 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. 1.681 − 497 =
2. 2.737 − 548 =
3. 3.604 − 538 =
4. 4.388 − 197 =
5. 5.824 − 187 =
6. 6.861 − 799 =
7. 7.326 − 198 =
8. 8.793 − 597 =
9. 9.951 − 429 =
10. 10.841 − 499 =
11. 11.534 − 228 =
12. 12.938 − 498 =
13. 13.986 − 289 =
14. 14.960 − 398 =
15. 15.650 − 628 =
16. 16.904 − 499 =
17. 17.776 − 299 =
18. 18.419 − 357 =
19. 19.585 − 189 =
20. 20.807 − 458 =
21. 21.832 − 647 =
22. 22.963 − 297 =
23. 23.710 − 539 =
24. 24.859 − 599 =
25. 25.472 − 129 =
26. 26.979 − 158 =
27. 27.551 − 187 =
28. 28.949 − 698 =
29. 29.949 − 699 =
30. 30.681 − 398 =
31. 31.890 − 797 =
32. 32.445 − 399 =
33. 33.585 − 497 =
34. 34.970 − 487 =
35. 35.709 − 557 =
36. 36.618 − 268 =
37. 37.925 − 478 =
38. 38.479 − 167 =
39. 39.482 − 447 =
40. 40.517 − 299 =

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