Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 396 · 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. 1.725 − 538 =
2. 2.699 − 387 =
3. 3.811 − 389 =
4. 4.914 − 797 =
5. 5.838 − 599 =
6. 6.865 − 297 =
7. 7.982 − 277 =
8. 8.248 − 199 =
9. 9.958 − 667 =
10. 10.926 − 798 =
11. 11.944 − 189 =
12. 12.698 − 678 =
13. 13.721 − 697 =
14. 14.708 − 667 =
15. 15.751 − 697 =
16. 16.946 − 698 =
17. 17.654 − 197 =
18. 18.911 − 688 =
19. 19.614 − 208 =
20. 20.922 − 299 =
21. 21.629 − 198 =
22. 22.681 − 499 =
23. 23.937 − 699 =
24. 24.435 − 409 =
25. 25.790 − 188 =
26. 26.751 − 679 =
27. 27.719 − 699 =
28. 28.817 − 499 =
29. 29.675 − 398 =
30. 30.482 − 199 =
31. 31.782 − 147 =
32. 32.635 − 499 =
33. 33.502 − 487 =
34. 34.884 − 199 =
35. 35.213 − 177 =
36. 36.556 − 118 =
37. 37.938 − 697 =
38. 38.308 − 237 =
39. 39.974 − 699 =
40. 40.421 − 179 =

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