Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 467 · 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. 1.492 − 299 =
2. 2.739 − 669 =
3. 3.783 − 397 =
4. 4.368 − 137 =
5. 5.847 − 638 =
6. 6.973 − 617 =
7. 7.830 − 597 =
8. 8.669 − 528 =
9. 9.475 − 398 =
10. 10.879 − 697 =
11. 11.459 − 398 =
12. 12.320 − 198 =
13. 13.819 − 199 =
14. 14.920 − 298 =
15. 15.822 − 499 =
16. 16.929 − 298 =
17. 17.645 − 167 =
18. 18.719 − 428 =
19. 19.375 − 299 =
20. 20.731 − 398 =
21. 21.928 − 339 =
22. 22.902 − 597 =
23. 23.631 − 198 =
24. 24.826 − 558 =
25. 25.875 − 199 =
26. 26.534 − 397 =
27. 27.396 − 199 =
28. 28.939 − 418 =
29. 29.654 − 387 =
30. 30.276 − 168 =
31. 31.823 − 499 =
32. 32.307 − 199 =
33. 33.312 − 298 =
34. 34.309 − 197 =
35. 35.858 − 798 =
36. 36.585 − 497 =
37. 37.790 − 399 =
38. 38.691 − 599 =
39. 39.559 − 298 =
40. 40.894 − 309 =

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