Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 968 · 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. 1.788 − 397 =
2. 2.792 − 497 =
3. 3.677 − 397 =
4. 4.617 − 548 =
5. 5.629 − 398 =
6. 6.726 − 697 =
7. 7.747 − 698 =
8. 8.703 − 618 =
9. 9.821 − 599 =
10. 10.893 − 597 =
11. 11.989 − 599 =
12. 12.573 − 397 =
13. 13.626 − 569 =
14. 14.758 − 437 =
15. 15.825 − 699 =
16. 16.984 − 498 =
17. 17.618 − 538 =
18. 18.992 − 598 =
19. 19.704 − 438 =
20. 20.643 − 398 =
21. 21.804 − 499 =
22. 22.918 − 798 =
23. 23.530 − 398 =
24. 24.890 − 797 =
25. 25.536 − 398 =
26. 26.757 − 397 =
27. 27.692 − 658 =
28. 28.843 − 399 =
29. 29.558 − 397 =
30. 30.568 − 477 =
31. 31.523 − 199 =
32. 32.980 − 669 =
33. 33.701 − 497 =
34. 34.814 − 498 =
35. 35.936 − 398 =
36. 36.625 − 558 =
37. 37.760 − 389 =
38. 38.664 − 598 =
39. 39.473 − 398 =
40. 40.443 − 399 =

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