Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 425 · 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. 1.906 − 198 =
2. 2.828 − 127 =
3. 3.705 − 597 =
4. 4.372 − 119 =
5. 5.243 − 227 =
6. 6.382 − 297 =
7. 7.850 − 599 =
8. 8.637 − 219 =
9. 9.229 − 197 =
10. 10.721 − 599 =
11. 11.727 − 299 =
12. 12.895 − 199 =
13. 13.840 − 539 =
14. 14.836 − 227 =
15. 15.677 − 459 =
16. 16.881 − 119 =
17. 17.967 − 547 =
18. 18.848 − 199 =
19. 19.789 − 539 =
20. 20.961 − 659 =
21. 21.633 − 457 =
22. 22.693 − 499 =
23. 23.262 − 137 =
24. 24.913 − 688 =
25. 25.325 − 139 =
26. 26.952 − 798 =
27. 27.919 − 599 =
28. 28.558 − 239 =
29. 29.815 − 627 =
30. 30.779 − 698 =
31. 31.711 − 197 =
32. 32.617 − 128 =
33. 33.446 − 397 =
34. 34.857 − 198 =
35. 35.637 − 399 =
36. 36.774 − 697 =
37. 37.671 − 219 =
38. 38.917 − 449 =
39. 39.689 − 497 =
40. 40.509 − 479 =

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