Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 7 · 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. 1.922 − 298 =
2. 2.882 − 699 =
3. 3.943 − 459 =
4. 4.876 − 599 =
5. 5.243 − 197 =
6. 6.221 − 197 =
7. 7.975 − 297 =
8. 8.646 − 198 =
9. 9.563 − 298 =
10. 10.523 − 477 =
11. 11.353 − 197 =
12. 12.871 − 699 =
13. 13.497 − 399 =
14. 14.522 − 499 =
15. 15.826 − 408 =
16. 16.336 − 138 =
17. 17.825 − 177 =
18. 18.234 − 208 =
19. 19.831 − 599 =
20. 20.899 − 299 =
21. 21.214 − 199 =
22. 22.940 − 697 =
23. 23.577 − 338 =
24. 24.841 − 597 =
25. 25.475 − 157 =
26. 26.896 − 197 =
27. 27.977 − 579 =
28. 28.598 − 209 =
29. 29.438 − 279 =
30. 30.746 − 548 =
31. 31.824 − 697 =
32. 32.814 − 198 =
33. 33.644 − 499 =
34. 34.287 − 198 =
35. 35.903 − 637 =
36. 36.989 − 399 =
37. 37.703 − 629 =
38. 38.998 − 588 =
39. 39.967 − 539 =
40. 40.993 − 797 =

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