Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 618 · 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. 1.558 − 259 =
2. 2.940 − 799 =
3. 3.652 − 298 =
4. 4.618 − 517 =
5. 5.983 − 538 =
6. 6.282 − 139 =
7. 7.663 − 298 =
8. 8.858 − 679 =
9. 9.829 − 597 =
10. 10.461 − 209 =
11. 11.921 − 597 =
12. 12.396 − 197 =
13. 13.579 − 499 =
14. 14.731 − 549 =
15. 15.488 − 399 =
16. 16.426 − 299 =
17. 17.868 − 199 =
18. 18.990 − 207 =
19. 19.519 − 297 =
20. 20.938 − 497 =
21. 21.581 − 297 =
22. 22.773 − 497 =
23. 23.805 − 208 =
24. 24.874 − 627 =
25. 25.667 − 458 =
26. 26.715 − 599 =
27. 27.902 − 697 =
28. 28.968 − 699 =
29. 29.708 − 499 =
30. 30.774 − 368 =
31. 31.830 − 797 =
32. 32.636 − 478 =
33. 33.732 − 397 =
34. 34.778 − 357 =
35. 35.511 − 387 =
36. 36.693 − 299 =
37. 37.662 − 609 =
38. 38.787 − 629 =
39. 39.932 − 478 =
40. 40.992 − 218 =

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