Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 585 · 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. 1.899 − 358 =
2. 2.492 − 289 =
3. 3.536 − 498 =
4. 4.577 − 479 =
5. 5.364 − 148 =
6. 6.419 − 397 =
7. 7.842 − 497 =
8. 8.804 − 699 =
9. 9.966 − 797 =
10. 10.886 − 598 =
11. 11.995 − 398 =
12. 12.697 − 397 =
13. 13.971 − 507 =
14. 14.453 − 288 =
15. 15.786 − 157 =
16. 16.474 − 397 =
17. 17.776 − 198 =
18. 18.704 − 398 =
19. 19.350 − 159 =
20. 20.387 − 168 =
21. 21.694 − 498 =
22. 22.219 − 198 =
23. 23.931 − 239 =
24. 24.518 − 298 =
25. 25.927 − 699 =
26. 26.870 − 589 =
27. 27.987 − 299 =
28. 28.989 − 278 =
29. 29.906 − 797 =
30. 30.971 − 687 =
31. 31.391 − 238 =
32. 32.331 − 298 =
33. 33.854 − 658 =
34. 34.800 − 198 =
35. 35.791 − 209 =
36. 36.932 − 699 =
37. 37.525 − 398 =
38. 38.976 − 598 =
39. 39.804 − 198 =
40. 40.929 − 679 =

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