Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 546 · 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. 1.551 − 439 =
2. 2.311 − 197 =
3. 3.884 − 198 =
4. 4.492 − 239 =
5. 5.900 − 169 =
6. 6.450 − 298 =
7. 7.862 − 599 =
8. 8.132 − 119 =
9. 9.928 − 517 =
10. 10.679 − 589 =
11. 11.726 − 537 =
12. 12.759 − 398 =
13. 13.734 − 688 =
14. 14.961 − 488 =
15. 15.973 − 299 =
16. 16.372 − 198 =
17. 17.719 − 249 =
18. 18.630 − 609 =
19. 19.653 − 577 =
20. 20.577 − 498 =
21. 21.532 − 498 =
22. 22.658 − 498 =
23. 23.659 − 398 =
24. 24.529 − 369 =
25. 25.583 − 207 =
26. 26.848 − 239 =
27. 27.896 − 598 =
28. 28.949 − 598 =
29. 29.408 − 199 =
30. 30.554 − 198 =
31. 31.908 − 399 =
32. 32.836 − 638 =
33. 33.864 − 198 =
34. 34.687 − 487 =
35. 35.938 − 498 =
36. 36.860 − 797 =
37. 37.983 − 399 =
38. 38.938 − 298 =
39. 39.881 − 799 =
40. 40.509 − 327 =

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