Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 761 · 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. 1.899 − 499 =
2. 2.573 − 508 =
3. 3.937 − 697 =
4. 4.734 − 399 =
5. 5.743 − 568 =
6. 6.760 − 549 =
7. 7.574 − 388 =
8. 8.934 − 418 =
9. 9.453 − 299 =
10. 10.967 − 618 =
11. 11.829 − 697 =
12. 12.336 − 298 =
13. 13.928 − 197 =
14. 14.671 − 638 =
15. 15.492 − 159 =
16. 16.789 − 198 =
17. 17.785 − 699 =
18. 18.824 − 299 =
19. 19.687 − 627 =
20. 20.517 − 248 =
21. 21.961 − 329 =
22. 22.887 − 698 =
23. 23.814 − 797 =
24. 24.522 − 499 =
25. 25.212 − 199 =
26. 26.367 − 328 =
27. 27.799 − 579 =
28. 28.978 − 389 =
29. 29.488 − 298 =
30. 30.358 − 159 =
31. 31.817 − 598 =
32. 32.648 − 199 =
33. 33.633 − 238 =
34. 34.926 − 658 =
35. 35.990 − 797 =
36. 36.746 − 399 =
37. 37.565 − 499 =
38. 38.593 − 217 =
39. 39.560 − 288 =
40. 40.785 − 349 =

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