Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 316 · 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. 1.911 − 798 =
2. 2.545 − 498 =
3. 3.937 − 497 =
4. 4.726 − 657 =
5. 5.892 − 599 =
6. 6.478 − 227 =
7. 7.468 − 299 =
8. 8.374 − 199 =
9. 9.563 − 399 =
10. 10.612 − 587 =
11. 11.929 − 669 =
12. 12.316 − 197 =
13. 13.680 − 297 =
14. 14.624 − 198 =
15. 15.883 − 597 =
16. 16.625 − 299 =
17. 17.256 − 197 =
18. 18.748 − 297 =
19. 19.874 − 348 =
20. 20.851 − 597 =
21. 21.863 − 577 =
22. 22.358 − 229 =
23. 23.967 − 698 =
24. 24.676 − 259 =
25. 25.589 − 518 =
26. 26.993 − 297 =
27. 27.773 − 508 =
28. 28.394 − 299 =
29. 29.993 − 799 =
30. 30.978 − 249 =
31. 31.504 − 487 =
32. 32.624 − 599 =
33. 33.953 − 799 =
34. 34.872 − 799 =
35. 35.702 − 687 =
36. 36.383 − 217 =
37. 37.739 − 278 =
38. 38.970 − 799 =
39. 39.929 − 397 =
40. 40.762 − 497 =

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