Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 509 · 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. 1.807 − 498 =
2. 2.620 − 549 =
3. 3.884 − 219 =
4. 4.607 − 249 =
5. 5.772 − 198 =
6. 6.553 − 499 =
7. 7.867 − 699 =
8. 8.441 − 297 =
9. 9.968 − 498 =
10. 10.597 − 399 =
11. 11.742 − 599 =
12. 12.548 − 318 =
13. 13.883 − 797 =
14. 14.790 − 597 =
15. 15.715 − 649 =
16. 16.703 − 297 =
17. 17.612 − 219 =
18. 18.926 − 238 =
19. 19.365 − 289 =
20. 20.433 − 397 =
21. 21.773 − 649 =
22. 22.740 − 298 =
23. 23.637 − 239 =
24. 24.888 − 797 =
25. 25.773 − 598 =
26. 26.320 − 219 =
27. 27.854 − 659 =
28. 28.907 − 299 =
29. 29.456 − 368 =
30. 30.570 − 497 =
31. 31.355 − 289 =
32. 32.872 − 698 =
33. 33.221 − 198 =
34. 34.618 − 348 =
35. 35.858 − 318 =
36. 36.702 − 317 =
37. 37.840 − 598 =
38. 38.607 − 297 =
39. 39.656 − 498 =
40. 40.624 − 399 =

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