Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 772 · 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. 1.928 − 799 =
2. 2.758 − 509 =
3. 3.602 − 159 =
4. 4.621 − 399 =
5. 5.772 − 608 =
6. 6.398 − 198 =
7. 7.961 − 697 =
8. 8.911 − 199 =
9. 9.510 − 148 =
10. 10.426 − 147 =
11. 11.884 − 297 =
12. 12.292 − 137 =
13. 13.751 − 327 =
14. 14.761 − 518 =
15. 15.692 − 599 =
16. 16.777 − 597 =
17. 17.642 − 498 =
18. 18.897 − 398 =
19. 19.278 − 247 =
20. 20.779 − 598 =
21. 21.974 − 699 =
22. 22.733 − 478 =
23. 23.285 − 258 =
24. 24.582 − 499 =
25. 25.825 − 618 =
26. 26.659 − 558 =
27. 27.863 − 199 =
28. 28.650 − 199 =
29. 29.770 − 497 =
30. 30.736 − 298 =
31. 31.517 − 477 =
32. 32.501 − 479 =
33. 33.632 − 399 =
34. 34.860 − 799 =
35. 35.873 − 599 =
36. 36.285 − 238 =
37. 37.510 − 297 =
38. 38.928 − 297 =
39. 39.514 − 299 =
40. 40.760 − 588 =

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