Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 294 · 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. 1.642 − 139 =
2. 2.873 − 179 =
3. 3.876 − 699 =
4. 4.804 − 457 =
5. 5.864 − 299 =
6. 6.954 − 398 =
7. 7.637 − 398 =
8. 8.894 − 698 =
9. 9.750 − 197 =
10. 10.598 − 547 =
11. 11.560 − 349 =
12. 12.787 − 697 =
13. 13.873 − 638 =
14. 14.986 − 798 =
15. 15.923 − 307 =
16. 16.807 − 258 =
17. 17.738 − 617 =
18. 18.898 − 219 =
19. 19.393 − 198 =
20. 20.544 − 118 =
21. 21.474 − 397 =
22. 22.268 − 197 =
23. 23.767 − 398 =
24. 24.516 − 499 =
25. 25.367 − 347 =
26. 26.444 − 367 =
27. 27.901 − 409 =
28. 28.469 − 197 =
29. 29.770 − 538 =
30. 30.788 − 699 =
31. 31.511 − 308 =
32. 32.649 − 499 =
33. 33.861 − 428 =
34. 34.758 − 438 =
35. 35.774 − 298 =
36. 36.456 − 369 =
37. 37.411 − 198 =
38. 38.930 − 299 =
39. 39.860 − 297 =
40. 40.913 − 698 =

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