Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 189 · 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. 1.647 − 597 =
2. 2.954 − 798 =
3. 3.845 − 799 =
4. 4.993 − 799 =
5. 5.855 − 798 =
6. 6.902 − 438 =
7. 7.724 − 598 =
8. 8.979 − 398 =
9. 9.461 − 299 =
10. 10.581 − 388 =
11. 11.889 − 499 =
12. 12.783 − 399 =
13. 13.940 − 478 =
14. 14.689 − 229 =
15. 15.562 − 218 =
16. 16.684 − 338 =
17. 17.955 − 289 =
18. 18.300 − 197 =
19. 19.969 − 349 =
20. 20.988 − 499 =
21. 21.843 − 399 =
22. 22.968 − 799 =
23. 23.961 − 269 =
24. 24.487 − 298 =
25. 25.630 − 597 =
26. 26.849 − 599 =
27. 27.751 − 189 =
28. 28.307 − 238 =
29. 29.842 − 428 =
30. 30.726 − 699 =
31. 31.629 − 599 =
32. 32.242 − 167 =
33. 33.650 − 497 =
34. 34.986 − 458 =
35. 35.378 − 269 =
36. 36.554 − 498 =
37. 37.857 − 499 =
38. 38.650 − 409 =
39. 39.414 − 198 =
40. 40.757 − 698 =

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