Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 597 · 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. 1.496 − 398 =
2. 2.976 − 517 =
3. 3.497 − 139 =
4. 4.950 − 797 =
5. 5.365 − 197 =
6. 6.643 − 559 =
7. 7.764 − 618 =
8. 8.864 − 419 =
9. 9.770 − 699 =
10. 10.742 − 509 =
11. 11.387 − 197 =
12. 12.678 − 589 =
13. 13.622 − 597 =
14. 14.690 − 199 =
15. 15.851 − 798 =
16. 16.536 − 507 =
17. 17.740 − 498 =
18. 18.424 − 318 =
19. 19.773 − 158 =
20. 20.829 − 799 =
21. 21.858 − 648 =
22. 22.445 − 399 =
23. 23.986 − 598 =
24. 24.942 − 499 =
25. 25.622 − 609 =
26. 26.527 − 199 =
27. 27.466 − 227 =
28. 28.683 − 298 =
29. 29.386 − 297 =
30. 30.263 − 227 =
31. 31.641 − 487 =
32. 32.612 − 197 =
33. 33.709 − 399 =
34. 34.679 − 218 =
35. 35.942 − 799 =
36. 36.968 − 798 =
37. 37.606 − 459 =
38. 38.891 − 799 =
39. 39.730 − 398 =
40. 40.735 − 698 =

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