Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 999 · 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. 1.840 − 598 =
2. 2.320 − 137 =
3. 3.624 − 588 =
4. 4.648 − 439 =
5. 5.760 − 518 =
6. 6.907 − 299 =
7. 7.645 − 408 =
8. 8.235 − 159 =
9. 9.720 − 597 =
10. 10.349 − 319 =
11. 11.995 − 129 =
12. 12.957 − 137 =
13. 13.712 − 298 =
14. 14.546 − 148 =
15. 15.510 − 298 =
16. 16.870 − 499 =
17. 17.596 − 497 =
18. 18.444 − 319 =
19. 19.449 − 398 =
20. 20.794 − 697 =
21. 21.586 − 197 =
22. 22.673 − 597 =
23. 23.640 − 397 =
24. 24.913 − 148 =
25. 25.810 − 257 =
26. 26.401 − 217 =
27. 27.545 − 399 =
28. 28.959 − 499 =
29. 29.849 − 257 =
30. 30.604 − 147 =
31. 31.728 − 497 =
32. 32.379 − 299 =
33. 33.659 − 517 =
34. 34.680 − 468 =
35. 35.547 − 199 =
36. 36.736 − 699 =
37. 37.660 − 229 =
38. 38.626 − 598 =
39. 39.640 − 477 =
40. 40.922 − 298 =

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