Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 916 · 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. 1.321 − 299 =
2. 2.638 − 499 =
3. 3.344 − 199 =
4. 4.988 − 798 =
5. 5.673 − 529 =
6. 6.368 − 187 =
7. 7.795 − 199 =
8. 8.671 − 229 =
9. 9.697 − 597 =
10. 10.674 − 197 =
11. 11.435 − 299 =
12. 12.396 − 379 =
13. 13.450 − 417 =
14. 14.741 − 299 =
15. 15.822 − 599 =
16. 16.494 − 229 =
17. 17.822 − 507 =
18. 18.814 − 697 =
19. 19.437 − 179 =
20. 20.520 − 198 =
21. 21.913 − 497 =
22. 22.838 − 197 =
23. 23.458 − 199 =
24. 24.660 − 498 =
25. 25.887 − 499 =
26. 26.809 − 697 =
27. 27.637 − 357 =
28. 28.354 − 197 =
29. 29.996 − 259 =
30. 30.890 − 498 =
31. 31.604 − 498 =
32. 32.866 − 588 =
33. 33.885 − 597 =
34. 34.693 − 408 =
35. 35.688 − 398 =
36. 36.927 − 699 =
37. 37.564 − 199 =
38. 38.683 − 609 =
39. 39.712 − 699 =
40. 40.298 − 178 =

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