Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 921 · 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. 1.854 − 399 =
2. 2.558 − 199 =
3. 3.957 − 597 =
4. 4.929 − 298 =
5. 5.804 − 298 =
6. 6.735 − 638 =
7. 7.724 − 608 =
8. 8.691 − 397 =
9. 9.729 − 679 =
10. 10.421 − 198 =
11. 11.926 − 498 =
12. 12.671 − 209 =
13. 13.828 − 439 =
14. 14.684 − 669 =
15. 15.433 − 299 =
16. 16.704 − 297 =
17. 17.655 − 598 =
18. 18.909 − 499 =
19. 19.908 − 448 =
20. 20.800 − 497 =
21. 21.309 − 268 =
22. 22.826 − 637 =
23. 23.892 − 698 =
24. 24.443 − 197 =
25. 25.467 − 409 =
26. 26.660 − 198 =
27. 27.653 − 538 =
28. 28.732 − 299 =
29. 29.399 − 378 =
30. 30.720 − 499 =
31. 31.929 − 577 =
32. 32.714 − 399 =
33. 33.836 − 679 =
34. 34.812 − 799 =
35. 35.949 − 578 =
36. 36.347 − 197 =
37. 37.468 − 397 =
38. 38.707 − 398 =
39. 39.226 − 188 =
40. 40.842 − 298 =

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