Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 675 · 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. 1.605 − 579 =
2. 2.355 − 297 =
3. 3.923 − 197 =
4. 4.845 − 297 =
5. 5.781 − 449 =
6. 6.840 − 497 =
7. 7.891 − 299 =
8. 8.723 − 667 =
9. 9.682 − 199 =
10. 10.545 − 499 =
11. 11.715 − 199 =
12. 12.752 − 429 =
13. 13.519 − 129 =
14. 14.509 − 399 =
15. 15.661 − 388 =
16. 16.832 − 799 =
17. 17.923 − 438 =
18. 18.287 − 199 =
19. 19.809 − 699 =
20. 20.404 − 369 =
21. 21.519 − 358 =
22. 22.638 − 397 =
23. 23.618 − 397 =
24. 24.750 − 497 =
25. 25.824 − 697 =
26. 26.905 − 489 =
27. 27.684 − 478 =
28. 28.603 − 259 =
29. 29.849 − 528 =
30. 30.927 − 399 =
31. 31.770 − 387 =
32. 32.990 − 568 =
33. 33.646 − 199 =
34. 34.877 − 797 =
35. 35.488 − 298 =
36. 36.982 − 399 =
37. 37.659 − 537 =
38. 38.834 − 797 =
39. 39.840 − 517 =
40. 40.756 − 267 =

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