Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 147 · 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. 1.788 − 199 =
2. 2.854 − 199 =
3. 3.861 − 598 =
4. 4.863 − 498 =
5. 5.472 − 299 =
6. 6.776 − 297 =
7. 7.523 − 398 =
8. 8.540 − 358 =
9. 9.957 − 399 =
10. 10.839 − 299 =
11. 11.663 − 297 =
12. 12.908 − 638 =
13. 13.547 − 299 =
14. 14.849 − 439 =
15. 15.862 − 498 =
16. 16.785 − 529 =
17. 17.234 − 149 =
18. 18.757 − 699 =
19. 19.613 − 587 =
20. 20.588 − 297 =
21. 21.477 − 399 =
22. 22.650 − 209 =
23. 23.629 − 298 =
24. 24.704 − 399 =
25. 25.737 − 218 =
26. 26.454 − 397 =
27. 27.797 − 199 =
28. 28.826 − 498 =
29. 29.727 − 669 =
30. 30.648 − 629 =
31. 31.740 − 229 =
32. 32.733 − 689 =
33. 33.736 − 647 =
34. 34.536 − 489 =
35. 35.705 − 597 =
36. 36.785 − 508 =
37. 37.761 − 327 =
38. 38.415 − 278 =
39. 39.955 − 187 =
40. 40.634 − 499 =

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