Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 637 · 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. 1.441 − 397 =
2. 2.789 − 499 =
3. 3.643 − 539 =
4. 4.645 − 199 =
5. 5.493 − 217 =
6. 6.504 − 478 =
7. 7.504 − 349 =
8. 8.553 − 197 =
9. 9.706 − 498 =
10. 10.967 − 298 =
11. 11.635 − 598 =
12. 12.328 − 159 =
13. 13.821 − 598 =
14. 14.861 − 497 =
15. 15.910 − 478 =
16. 16.688 − 499 =
17. 17.780 − 497 =
18. 18.512 − 298 =
19. 19.213 − 197 =
20. 20.840 − 568 =
21. 21.563 − 469 =
22. 22.235 − 157 =
23. 23.760 − 609 =
24. 24.448 − 198 =
25. 25.419 − 197 =
26. 26.543 − 499 =
27. 27.549 − 398 =
28. 28.464 − 399 =
29. 29.806 − 638 =
30. 30.784 − 577 =
31. 31.734 − 697 =
32. 32.733 − 197 =
33. 33.818 − 497 =
34. 34.761 − 268 =
35. 35.989 − 499 =
36. 36.927 − 597 =
37. 37.568 − 399 =
38. 38.755 − 198 =
39. 39.612 − 597 =
40. 40.354 − 198 =

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