Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 519 · 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. 1.505 − 299 =
2. 2.347 − 297 =
3. 3.999 − 698 =
4. 4.636 − 199 =
5. 5.752 − 609 =
6. 6.806 − 429 =
7. 7.467 − 379 =
8. 8.965 − 698 =
9. 9.447 − 137 =
10. 10.938 − 457 =
11. 11.515 − 437 =
12. 12.740 − 557 =
13. 13.660 − 599 =
14. 14.791 − 697 =
15. 15.801 − 179 =
16. 16.619 − 599 =
17. 17.912 − 798 =
18. 18.872 − 199 =
19. 19.350 − 297 =
20. 20.828 − 798 =
21. 21.443 − 429 =
22. 22.920 − 627 =
23. 23.807 − 218 =
24. 24.670 − 348 =
25. 25.483 − 299 =
26. 26.752 − 438 =
27. 27.414 − 387 =
28. 28.762 − 667 =
29. 29.847 − 398 =
30. 30.985 − 597 =
31. 31.734 − 699 =
32. 32.886 − 567 =
33. 33.997 − 377 =
34. 34.679 − 599 =
35. 35.985 − 227 =
36. 36.562 − 449 =
37. 37.784 − 288 =
38. 38.985 − 197 =
39. 39.834 − 297 =
40. 40.648 − 548 =

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