Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 113 · 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. 1.940 − 399 =
2. 2.413 − 197 =
3. 3.890 − 599 =
4. 4.547 − 239 =
5. 5.397 − 159 =
6. 6.888 − 797 =
7. 7.936 − 299 =
8. 8.219 − 199 =
9. 9.794 − 599 =
10. 10.897 − 498 =
11. 11.932 − 487 =
12. 12.951 − 627 =
13. 13.540 − 197 =
14. 14.691 − 398 =
15. 15.632 − 268 =
16. 16.724 − 619 =
17. 17.688 − 398 =
18. 18.996 − 797 =
19. 19.568 − 499 =
20. 20.600 − 198 =
21. 21.706 − 228 =
22. 22.610 − 247 =
23. 23.923 − 798 =
24. 24.842 − 498 =
25. 25.688 − 598 =
26. 26.895 − 457 =
27. 27.650 − 198 =
28. 28.795 − 498 =
29. 29.784 − 679 =
30. 30.651 − 598 =
31. 31.684 − 597 =
32. 32.946 − 668 =
33. 33.857 − 698 =
34. 34.741 − 659 =
35. 35.655 − 298 =
36. 36.182 − 169 =
37. 37.596 − 199 =
38. 38.880 − 799 =
39. 39.194 − 137 =
40. 40.462 − 297 =

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