Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 646 · 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. 1.583 − 198 =
2. 2.770 − 299 =
3. 3.938 − 698 =
4. 4.636 − 478 =
5. 5.993 − 698 =
6. 6.924 − 598 =
7. 7.925 − 799 =
8. 8.763 − 699 =
9. 9.456 − 399 =
10. 10.826 − 799 =
11. 11.731 − 699 =
12. 12.694 − 519 =
13. 13.920 − 477 =
14. 14.676 − 429 =
15. 15.315 − 179 =
16. 16.365 − 237 =
17. 17.379 − 197 =
18. 18.646 − 487 =
19. 19.768 − 498 =
20. 20.811 − 589 =
21. 21.686 − 418 =
22. 22.745 − 687 =
23. 23.659 − 599 =
24. 24.939 − 199 =
25. 25.685 − 579 =
26. 26.959 − 597 =
27. 27.261 − 229 =
28. 28.836 − 799 =
29. 29.778 − 597 =
30. 30.481 − 437 =
31. 31.715 − 398 =
32. 32.956 − 499 =
33. 33.956 − 699 =
34. 34.683 − 399 =
35. 35.785 − 629 =
36. 36.738 − 278 =
37. 37.859 − 398 =
38. 38.652 − 497 =
39. 39.681 − 298 =
40. 40.550 − 199 =

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