Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 845 · 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. 1.445 − 308 =
2. 2.958 − 397 =
3. 3.614 − 397 =
4. 4.427 − 398 =
5. 5.421 − 119 =
6. 6.887 − 598 =
7. 7.841 − 797 =
8. 8.937 − 399 =
9. 9.940 − 698 =
10. 10.457 − 209 =
11. 11.596 − 558 =
12. 12.833 − 597 =
13. 13.517 − 447 =
14. 14.731 − 199 =
15. 15.541 − 499 =
16. 16.938 − 599 =
17. 17.755 − 319 =
18. 18.307 − 198 =
19. 19.649 − 509 =
20. 20.647 − 598 =
21. 21.983 − 397 =
22. 22.470 − 399 =
23. 23.509 − 227 =
24. 24.455 − 297 =
25. 25.823 − 177 =
26. 26.690 − 599 =
27. 27.464 − 298 =
28. 28.856 − 499 =
29. 29.566 − 239 =
30. 30.313 − 228 =
31. 31.805 − 697 =
32. 32.795 − 197 =
33. 33.358 − 128 =
34. 34.312 − 199 =
35. 35.335 − 198 =
36. 36.956 − 399 =
37. 37.975 − 399 =
38. 38.782 − 689 =
39. 39.204 − 137 =
40. 40.988 − 499 =

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