Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 321 · 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. 1.784 − 697 =
2. 2.326 − 297 =
3. 3.303 − 198 =
4. 4.464 − 398 =
5. 5.659 − 599 =
6. 6.425 − 359 =
7. 7.969 − 597 =
8. 8.373 − 197 =
9. 9.862 − 189 =
10. 10.694 − 549 =
11. 11.306 − 198 =
12. 12.861 − 799 =
13. 13.341 − 258 =
14. 14.504 − 429 =
15. 15.597 − 499 =
16. 16.331 − 158 =
17. 17.447 − 329 =
18. 18.635 − 277 =
19. 19.698 − 459 =
20. 20.931 − 447 =
21. 21.781 − 159 =
22. 22.862 − 299 =
23. 23.592 − 579 =
24. 24.351 − 158 =
25. 25.989 − 698 =
26. 26.830 − 139 =
27. 27.736 − 347 =
28. 28.931 − 397 =
29. 29.743 − 388 =
30. 30.187 − 118 =
31. 31.614 − 298 =
32. 32.884 − 488 =
33. 33.410 − 189 =
34. 34.621 − 598 =
35. 35.825 − 198 =
36. 36.792 − 597 =
37. 37.541 − 349 =
38. 38.525 − 358 =
39. 39.402 − 329 =
40. 40.830 − 199 =

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