Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 367 · 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. 1.812 − 298 =
2. 2.782 − 338 =
3. 3.779 − 598 =
4. 4.882 − 359 =
5. 5.802 − 268 =
6. 6.431 − 298 =
7. 7.691 − 558 =
8. 8.276 − 198 =
9. 9.610 − 299 =
10. 10.902 − 698 =
11. 11.978 − 568 =
12. 12.538 − 158 =
13. 13.966 − 797 =
14. 14.251 − 199 =
15. 15.790 − 529 =
16. 16.775 − 697 =
17. 17.704 − 198 =
18. 18.807 − 598 =
19. 19.749 − 459 =
20. 20.501 − 409 =
21. 21.882 − 797 =
22. 22.399 − 169 =
23. 23.617 − 248 =
24. 24.579 − 498 =
25. 25.705 − 359 =
26. 26.817 − 697 =
27. 27.605 − 297 =
28. 28.515 − 499 =
29. 29.925 − 197 =
30. 30.662 − 548 =
31. 31.630 − 198 =
32. 32.632 − 499 =
33. 33.856 − 798 =
34. 34.740 − 599 =
35. 35.695 − 629 =
36. 36.778 − 207 =
37. 37.593 − 399 =
38. 38.611 − 199 =
39. 39.612 − 199 =
40. 40.950 − 397 =

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