Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 518 · 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. 1.752 − 699 =
2. 2.862 − 799 =
3. 3.903 − 798 =
4. 4.642 − 429 =
5. 5.908 − 197 =
6. 6.654 − 198 =
7. 7.884 − 637 =
8. 8.652 − 399 =
9. 9.752 − 299 =
10. 10.657 − 238 =
11. 11.804 − 699 =
12. 12.770 − 608 =
13. 13.836 − 279 =
14. 14.886 − 477 =
15. 15.820 − 797 =
16. 16.777 − 499 =
17. 17.796 − 149 =
18. 18.865 − 797 =
19. 19.445 − 238 =
20. 20.660 − 299 =
21. 21.650 − 599 =
22. 22.942 − 299 =
23. 23.843 − 638 =
24. 24.872 − 449 =
25. 25.814 − 597 =
26. 26.742 − 398 =
27. 27.698 − 399 =
28. 28.642 − 577 =
29. 29.951 − 399 =
30. 30.287 − 169 =
31. 31.886 − 398 =
32. 32.699 − 499 =
33. 33.800 − 408 =
34. 34.751 − 598 =
35. 35.781 − 448 =
36. 36.596 − 519 =
37. 37.900 − 197 =
38. 38.856 − 257 =
39. 39.773 − 689 =
40. 40.910 − 498 =

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