Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 100 · 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. 1.739 − 419 =
2. 2.379 − 217 =
3. 3.428 − 199 =
4. 4.966 − 499 =
5. 5.698 − 247 =
6. 6.941 − 598 =
7. 7.563 − 179 =
8. 8.836 − 687 =
9. 9.840 − 297 =
10. 10.739 − 688 =
11. 11.892 − 399 =
12. 12.654 − 547 =
13. 13.283 − 197 =
14. 14.614 − 177 =
15. 15.511 − 299 =
16. 16.545 − 297 =
17. 17.598 − 297 =
18. 18.298 − 217 =
19. 19.934 − 797 =
20. 20.750 − 599 =
21. 21.865 − 797 =
22. 22.937 − 429 =
23. 23.579 − 168 =
24. 24.504 − 399 =
25. 25.339 − 188 =
26. 26.666 − 549 =
27. 27.955 − 799 =
28. 28.316 − 139 =
29. 29.573 − 348 =
30. 30.826 − 498 =
31. 31.983 − 699 =
32. 32.450 − 358 =
33. 33.653 − 597 =
34. 34.940 − 519 =
35. 35.660 − 397 =
36. 36.670 − 548 =
37. 37.860 − 298 =
38. 38.976 − 799 =
39. 39.979 − 267 =
40. 40.884 − 498 =

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