Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 655 · 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. 1.438 − 398 =
2. 2.333 − 217 =
3. 3.696 − 498 =
4. 4.862 − 298 =
5. 5.604 − 507 =
6. 6.700 − 177 =
7. 7.923 − 399 =
8. 8.600 − 528 =
9. 9.941 − 698 =
10. 10.789 − 557 =
11. 11.654 − 548 =
12. 12.801 − 659 =
13. 13.676 − 197 =
14. 14.941 − 649 =
15. 15.950 − 799 =
16. 16.239 − 197 =
17. 17.511 − 298 =
18. 18.734 − 199 =
19. 19.638 − 397 =
20. 20.708 − 599 =
21. 21.913 − 379 =
22. 22.704 − 618 =
23. 23.732 − 297 =
24. 24.778 − 697 =
25. 25.642 − 599 =
26. 26.871 − 598 =
27. 27.981 − 797 =
28. 28.910 − 599 =
29. 29.900 − 797 =
30. 30.416 − 397 =
31. 31.757 − 597 =
32. 32.861 − 198 =
33. 33.818 − 698 =
34. 34.983 − 798 =
35. 35.441 − 307 =
36. 36.765 − 599 =
37. 37.465 − 398 =
38. 38.507 − 299 =
39. 39.503 − 299 =
40. 40.983 − 398 =

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