Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 734 · 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. 1.658 − 478 =
2. 2.721 − 198 =
3. 3.963 − 397 =
4. 4.917 − 698 =
5. 5.496 − 429 =
6. 6.875 − 518 =
7. 7.741 − 299 =
8. 8.396 − 299 =
9. 9.603 − 557 =
10. 10.576 − 499 =
11. 11.919 − 597 =
12. 12.572 − 399 =
13. 13.427 − 198 =
14. 14.785 − 199 =
15. 15.472 − 199 =
16. 16.912 − 699 =
17. 17.792 − 499 =
18. 18.341 − 158 =
19. 19.740 − 598 =
20. 20.779 − 199 =
21. 21.748 − 397 =
22. 22.578 − 399 =
23. 23.516 − 197 =
24. 24.794 − 399 =
25. 25.763 − 498 =
26. 26.974 − 297 =
27. 27.516 − 338 =
28. 28.438 − 399 =
29. 29.966 − 797 =
30. 30.919 − 279 =
31. 31.684 − 218 =
32. 32.952 − 609 =
33. 33.505 − 328 =
34. 34.427 − 197 =
35. 35.803 − 298 =
36. 36.734 − 688 =
37. 37.446 − 297 =
38. 38.999 − 197 =
39. 39.736 − 699 =
40. 40.707 − 597 =

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