Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 779 · 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. 1.457 − 299 =
2. 2.441 − 397 =
3. 3.564 − 398 =
4. 4.889 − 699 =
5. 5.963 − 508 =
6. 6.598 − 327 =
7. 7.640 − 169 =
8. 8.389 − 198 =
9. 9.903 − 397 =
10. 10.876 − 218 =
11. 11.709 − 499 =
12. 12.657 − 599 =
13. 13.433 − 197 =
14. 14.723 − 587 =
15. 15.680 − 598 =
16. 16.412 − 249 =
17. 17.198 − 129 =
18. 18.878 − 399 =
19. 19.816 − 797 =
20. 20.771 − 198 =
21. 21.930 − 487 =
22. 22.535 − 358 =
23. 23.790 − 397 =
24. 24.855 − 667 =
25. 25.255 − 119 =
26. 26.949 − 698 =
27. 27.778 − 698 =
28. 28.706 − 369 =
29. 29.734 − 398 =
30. 30.454 − 399 =
31. 31.615 − 477 =
32. 32.349 − 198 =
33. 33.739 − 199 =
34. 34.630 − 547 =
35. 35.578 − 419 =
36. 36.378 − 298 =
37. 37.157 − 129 =
38. 38.680 − 298 =
39. 39.685 − 409 =
40. 40.949 − 509 =

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