Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 331 · 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. 1.833 − 699 =
2. 2.395 − 198 =
3. 3.536 − 429 =
4. 4.878 − 297 =
5. 5.851 − 359 =
6. 6.894 − 397 =
7. 7.638 − 369 =
8. 8.963 − 499 =
9. 9.865 − 798 =
10. 10.958 − 799 =
11. 11.816 − 629 =
12. 12.675 − 478 =
13. 13.583 − 199 =
14. 14.976 − 639 =
15. 15.954 − 558 =
16. 16.833 − 698 =
17. 17.995 − 199 =
18. 18.972 − 497 =
19. 19.622 − 298 =
20. 20.540 − 399 =
21. 21.983 − 119 =
22. 22.992 − 197 =
23. 23.931 − 588 =
24. 24.437 − 397 =
25. 25.877 − 198 =
26. 26.997 − 797 =
27. 27.872 − 597 =
28. 28.337 − 297 =
29. 29.721 − 299 =
30. 30.597 − 209 =
31. 31.908 − 798 =
32. 32.993 − 638 =
33. 33.696 − 398 =
34. 34.889 − 799 =
35. 35.339 − 309 =
36. 36.779 − 599 =
37. 37.715 − 417 =
38. 38.935 − 497 =
39. 39.989 − 377 =
40. 40.164 − 128 =

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