Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 88 · 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. 1.447 − 299 =
2. 2.904 − 599 =
3. 3.942 − 579 =
4. 4.585 − 419 =
5. 5.885 − 597 =
6. 6.880 − 507 =
7. 7.846 − 658 =
8. 8.527 − 447 =
9. 9.612 − 559 =
10. 10.921 − 637 =
11. 11.931 − 698 =
12. 12.904 − 398 =
13. 13.707 − 458 =
14. 14.536 − 338 =
15. 15.717 − 648 =
16. 16.671 − 609 =
17. 17.691 − 597 =
18. 18.904 − 498 =
19. 19.889 − 199 =
20. 20.312 − 248 =
21. 21.513 − 458 =
22. 22.675 − 548 =
23. 23.998 − 599 =
24. 24.926 − 568 =
25. 25.668 − 197 =
26. 26.607 − 467 =
27. 27.982 − 797 =
28. 28.655 − 197 =
29. 29.706 − 659 =
30. 30.788 − 698 =
31. 31.672 − 598 =
32. 32.294 − 198 =
33. 33.782 − 417 =
34. 34.283 − 197 =
35. 35.349 − 299 =
36. 36.746 − 379 =
37. 37.600 − 228 =
38. 38.994 − 539 =
39. 39.786 − 518 =
40. 40.943 − 587 =

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