Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 436 · 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. 1.321 − 199 =
2. 2.701 − 198 =
3. 3.800 − 429 =
4. 4.929 − 799 =
5. 5.719 − 198 =
6. 6.995 − 598 =
7. 7.630 − 167 =
8. 8.809 − 209 =
9. 9.895 − 698 =
10. 10.936 − 399 =
11. 11.990 − 299 =
12. 12.593 − 129 =
13. 13.898 − 599 =
14. 14.699 − 298 =
15. 15.510 − 397 =
16. 16.657 − 198 =
17. 17.801 − 369 =
18. 18.790 − 299 =
19. 19.756 − 597 =
20. 20.841 − 658 =
21. 21.984 − 487 =
22. 22.682 − 277 =
23. 23.903 − 298 =
24. 24.994 − 138 =
25. 25.857 − 598 =
26. 26.618 − 399 =
27. 27.705 − 297 =
28. 28.969 − 599 =
29. 29.590 − 548 =
30. 30.696 − 399 =
31. 31.719 − 679 =
32. 32.578 − 418 =
33. 33.741 − 599 =
34. 34.676 − 497 =
35. 35.860 − 799 =
36. 36.642 − 599 =
37. 37.976 − 797 =
38. 38.588 − 278 =
39. 39.642 − 149 =
40. 40.430 − 398 =

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