Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 625 · 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. 1.821 − 168 =
2. 2.553 − 197 =
3. 3.968 − 607 =
4. 4.547 − 499 =
5. 5.817 − 597 =
6. 6.371 − 298 =
7. 7.941 − 599 =
8. 8.592 − 497 =
9. 9.572 − 377 =
10. 10.932 − 687 =
11. 11.330 − 199 =
12. 12.731 − 199 =
13. 13.559 − 327 =
14. 14.968 − 697 =
15. 15.890 − 419 =
16. 16.938 − 698 =
17. 17.629 − 448 =
18. 18.822 − 608 =
19. 19.751 − 277 =
20. 20.320 − 199 =
21. 21.771 − 297 =
22. 22.905 − 198 =
23. 23.349 − 268 =
24. 24.931 − 599 =
25. 25.234 − 197 =
26. 26.637 − 598 =
27. 27.908 − 797 =
28. 28.232 − 169 =
29. 29.952 − 559 =
30. 30.963 − 359 =
31. 31.442 − 347 =
32. 32.989 − 149 =
33. 33.942 − 689 =
34. 34.225 − 139 =
35. 35.671 − 298 =
36. 36.775 − 697 =
37. 37.810 − 578 =
38. 38.784 − 578 =
39. 39.670 − 597 =
40. 40.791 − 298 =

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