Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 458 · 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. 1.733 − 518 =
2. 2.269 − 169 =
3. 3.830 − 198 =
4. 4.266 − 198 =
5. 5.862 − 597 =
6. 6.711 − 689 =
7. 7.977 − 638 =
8. 8.670 − 298 =
9. 9.506 − 397 =
10. 10.899 − 697 =
11. 11.471 − 299 =
12. 12.595 − 497 =
13. 13.494 − 477 =
14. 14.925 − 618 =
15. 15.833 − 799 =
16. 16.415 − 297 =
17. 17.951 − 507 =
18. 18.941 − 678 =
19. 19.544 − 299 =
20. 20.873 − 298 =
21. 21.845 − 698 =
22. 22.618 − 397 =
23. 23.633 − 597 =
24. 24.547 − 197 =
25. 25.672 − 299 =
26. 26.928 − 398 =
27. 27.578 − 468 =
28. 28.494 − 397 =
29. 29.907 − 499 =
30. 30.917 − 328 =
31. 31.918 − 298 =
32. 32.916 − 428 =
33. 33.509 − 257 =
34. 34.573 − 219 =
35. 35.513 − 299 =
36. 36.581 − 139 =
37. 37.374 − 187 =
38. 38.737 − 497 =
39. 39.756 − 577 =
40. 40.370 − 298 =

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