Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 974 · 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. 1.831 − 599 =
2. 2.643 − 517 =
3. 3.809 − 297 =
4. 4.930 − 499 =
5. 5.353 − 218 =
6. 6.318 − 198 =
7. 7.463 − 397 =
8. 8.993 − 228 =
9. 9.472 − 278 =
10. 10.816 − 628 =
11. 11.838 − 519 =
12. 12.712 − 298 =
13. 13.873 − 118 =
14. 14.709 − 498 =
15. 15.406 − 247 =
16. 16.783 − 598 =
17. 17.894 − 517 =
18. 18.864 − 378 =
19. 19.974 − 197 =
20. 20.756 − 368 =
21. 21.382 − 139 =
22. 22.711 − 638 =
23. 23.762 − 598 =
24. 24.629 − 598 =
25. 25.658 − 299 =
26. 26.378 − 198 =
27. 27.804 − 198 =
28. 28.655 − 448 =
29. 29.427 − 319 =
30. 30.392 − 199 =
31. 31.878 − 799 =
32. 32.635 − 609 =
33. 33.897 − 629 =
34. 34.740 − 507 =
35. 35.840 − 679 =
36. 36.588 − 519 =
37. 37.930 − 799 =
38. 38.899 − 557 =
39. 39.894 − 299 =
40. 40.475 − 297 =

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