Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 666 · 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. 1.821 − 298 =
2. 2.837 − 399 =
3. 3.282 − 197 =
4. 4.891 − 438 =
5. 5.864 − 427 =
6. 6.653 − 597 =
7. 7.765 − 598 =
8. 8.846 − 799 =
9. 9.912 − 487 =
10. 10.491 − 228 =
11. 11.924 − 798 =
12. 12.699 − 498 =
13. 13.538 − 299 =
14. 14.765 − 457 =
15. 15.701 − 399 =
16. 16.596 − 397 =
17. 17.580 − 438 =
18. 18.788 − 618 =
19. 19.986 − 139 =
20. 20.349 − 297 =
21. 21.907 − 598 =
22. 22.482 − 119 =
23. 23.716 − 468 =
24. 24.845 − 199 =
25. 25.618 − 199 =
26. 26.844 − 667 =
27. 27.805 − 197 =
28. 28.683 − 587 =
29. 29.549 − 299 =
30. 30.569 − 468 =
31. 31.716 − 168 =
32. 32.893 − 539 =
33. 33.774 − 297 =
34. 34.453 − 298 =
35. 35.672 − 399 =
36. 36.416 − 298 =
37. 37.822 − 149 =
38. 38.423 − 199 =
39. 39.486 − 429 =
40. 40.890 − 499 =

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