Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 161 · 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. 1.338 − 289 =
2. 2.851 − 799 =
3. 3.868 − 598 =
4. 4.678 − 609 =
5. 5.818 − 139 =
6. 6.812 − 549 =
7. 7.645 − 479 =
8. 8.314 − 298 =
9. 9.890 − 338 =
10. 10.571 − 297 =
11. 11.736 − 198 =
12. 12.766 − 149 =
13. 13.810 − 638 =
14. 14.348 − 247 =
15. 15.973 − 588 =
16. 16.927 − 378 =
17. 17.771 − 597 =
18. 18.927 − 607 =
19. 19.960 − 337 =
20. 20.443 − 299 =
21. 21.715 − 698 =
22. 22.653 − 598 =
23. 23.456 − 198 =
24. 24.580 − 158 =
25. 25.794 − 559 =
26. 26.815 − 357 =
27. 27.618 − 599 =
28. 28.406 − 197 =
29. 29.942 − 797 =
30. 30.430 − 199 =
31. 31.943 − 619 =
32. 32.811 − 508 =
33. 33.536 − 397 =
34. 34.751 − 478 =
35. 35.251 − 198 =
36. 36.760 − 699 =
37. 37.941 − 438 =
38. 38.405 − 188 =
39. 39.537 − 399 =
40. 40.344 − 209 =

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