Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 470 · 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. 1.791 − 298 =
2. 2.942 − 378 =
3. 3.719 − 499 =
4. 4.767 − 388 =
5. 5.586 − 477 =
6. 6.642 − 348 =
7. 7.380 − 197 =
8. 8.992 − 397 =
9. 9.329 − 269 =
10. 10.812 − 198 =
11. 11.922 − 597 =
12. 12.614 − 299 =
13. 13.913 − 338 =
14. 14.803 − 278 =
15. 15.697 − 598 =
16. 16.625 − 529 =
17. 17.706 − 199 =
18. 18.749 − 698 =
19. 19.635 − 597 =
20. 20.282 − 197 =
21. 21.819 − 157 =
22. 22.945 − 547 =
23. 23.861 − 497 =
24. 24.492 − 298 =
25. 25.844 − 219 =
26. 26.946 − 598 =
27. 27.989 − 497 =
28. 28.797 − 417 =
29. 29.792 − 538 =
30. 30.967 − 697 =
31. 31.639 − 467 =
32. 32.962 − 799 =
33. 33.640 − 517 =
34. 34.346 − 127 =
35. 35.478 − 449 =
36. 36.789 − 417 =
37. 37.609 − 498 =
38. 38.705 − 197 =
39. 39.831 − 799 =
40. 40.545 − 508 =

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