Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 481 · 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. 1.664 − 398 =
2. 2.751 − 359 =
3. 3.791 − 697 =
4. 4.563 − 499 =
5. 5.865 − 509 =
6. 6.917 − 298 =
7. 7.945 − 198 =
8. 8.726 − 397 =
9. 9.954 − 699 =
10. 10.992 − 218 =
11. 11.396 − 207 =
12. 12.905 − 299 =
13. 13.583 − 488 =
14. 14.709 − 497 =
15. 15.786 − 698 =
16. 16.958 − 497 =
17. 17.453 − 297 =
18. 18.942 − 279 =
19. 19.758 − 209 =
20. 20.337 − 197 =
21. 21.933 − 397 =
22. 22.763 − 398 =
23. 23.681 − 599 =
24. 24.691 − 397 =
25. 25.499 − 419 =
26. 26.642 − 299 =
27. 27.247 − 179 =
28. 28.815 − 617 =
29. 29.846 − 797 =
30. 30.688 − 397 =
31. 31.833 − 177 =
32. 32.475 − 439 =
33. 33.928 − 529 =
34. 34.628 − 498 =
35. 35.617 − 498 =
36. 36.757 − 209 =
37. 37.838 − 299 =
38. 38.811 − 499 =
39. 39.762 − 489 =
40. 40.359 − 329 =

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