Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 649 · 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. 1.600 − 198 =
2. 2.997 − 697 =
3. 3.522 − 299 =
4. 4.716 − 179 =
5. 5.618 − 509 =
6. 6.573 − 218 =
7. 7.897 − 599 =
8. 8.765 − 599 =
9. 9.583 − 298 =
10. 10.699 − 299 =
11. 11.519 − 477 =
12. 12.478 − 119 =
13. 13.957 − 498 =
14. 14.453 − 409 =
15. 15.756 − 379 =
16. 16.900 − 799 =
17. 17.481 − 149 =
18. 18.990 − 498 =
19. 19.322 − 297 =
20. 20.649 − 429 =
21. 21.526 − 508 =
22. 22.278 − 118 =
23. 23.825 − 698 =
24. 24.474 − 399 =
25. 25.463 − 349 =
26. 26.985 − 419 =
27. 27.880 − 799 =
28. 28.682 − 197 =
29. 29.622 − 529 =
30. 30.656 − 177 =
31. 31.478 − 278 =
32. 32.722 − 598 =
33. 33.714 − 599 =
34. 34.899 − 657 =
35. 35.893 − 397 =
36. 36.525 − 379 =
37. 37.798 − 297 =
38. 38.963 − 299 =
39. 39.718 − 129 =
40. 40.569 − 339 =

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