Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 870 · 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. 1.451 − 137 =
2. 2.790 − 198 =
3. 3.647 − 599 =
4. 4.931 − 397 =
5. 5.980 − 799 =
6. 6.640 − 598 =
7. 7.595 − 537 =
8. 8.324 − 237 =
9. 9.710 − 608 =
10. 10.332 − 308 =
11. 11.649 − 397 =
12. 12.798 − 668 =
13. 13.564 − 507 =
14. 14.770 − 397 =
15. 15.955 − 678 =
16. 16.702 − 188 =
17. 17.695 − 137 =
18. 18.731 − 297 =
19. 19.993 − 517 =
20. 20.392 − 329 =
21. 21.664 − 299 =
22. 22.946 − 139 =
23. 23.634 − 397 =
24. 24.407 − 238 =
25. 25.847 − 448 =
26. 26.864 − 358 =
27. 27.285 − 158 =
28. 28.879 − 798 =
29. 29.671 − 499 =
30. 30.919 − 289 =
31. 31.742 − 478 =
32. 32.492 − 197 =
33. 33.247 − 199 =
34. 34.972 − 698 =
35. 35.844 − 198 =
36. 36.986 − 799 =
37. 37.381 − 199 =
38. 38.850 − 597 =
39. 39.342 − 299 =
40. 40.716 − 597 =

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