Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 293 · 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. 1.644 − 297 =
2. 2.879 − 699 =
3. 3.803 − 677 =
4. 4.717 − 298 =
5. 5.852 − 397 =
6. 6.856 − 297 =
7. 7.825 − 178 =
8. 8.590 − 498 =
9. 9.443 − 199 =
10. 10.952 − 347 =
11. 11.253 − 218 =
12. 12.626 − 247 =
13. 13.887 − 247 =
14. 14.777 − 518 =
15. 15.630 − 408 =
16. 16.652 − 298 =
17. 17.223 − 179 =
18. 18.432 − 397 =
19. 19.698 − 618 =
20. 20.691 − 589 =
21. 21.790 − 158 =
22. 22.362 − 328 =
23. 23.653 − 599 =
24. 24.636 − 298 =
25. 25.707 − 307 =
26. 26.946 − 699 =
27. 27.415 − 118 =
28. 28.406 − 249 =
29. 29.975 − 589 =
30. 30.928 − 797 =
31. 31.980 − 399 =
32. 32.820 − 798 =
33. 33.872 − 799 =
34. 34.913 − 398 =
35. 35.710 − 197 =
36. 36.409 − 267 =
37. 37.845 − 498 =
38. 38.633 − 587 =
39. 39.447 − 397 =
40. 40.534 − 498 =

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