Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 414 · 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. 1.854 − 117 =
2. 2.639 − 609 =
3. 3.640 − 478 =
4. 4.688 − 169 =
5. 5.842 − 198 =
6. 6.685 − 299 =
7. 7.883 − 179 =
8. 8.349 − 299 =
9. 9.662 − 247 =
10. 10.311 − 158 =
11. 11.563 − 399 =
12. 12.884 − 609 =
13. 13.903 − 698 =
14. 14.991 − 699 =
15. 15.927 − 497 =
16. 16.872 − 297 =
17. 17.876 − 338 =
18. 18.635 − 519 =
19. 19.693 − 197 =
20. 20.796 − 598 =
21. 21.465 − 438 =
22. 22.931 − 599 =
23. 23.549 − 199 =
24. 24.990 − 529 =
25. 25.725 − 697 =
26. 26.846 − 529 =
27. 27.489 − 199 =
28. 28.991 − 299 =
29. 29.642 − 599 =
30. 30.982 − 477 =
31. 31.988 − 698 =
32. 32.845 − 297 =
33. 33.693 − 199 =
34. 34.950 − 529 =
35. 35.540 − 249 =
36. 36.419 − 137 =
37. 37.936 − 698 =
38. 38.868 − 598 =
39. 39.942 − 157 =
40. 40.372 − 298 =

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