Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 365 · 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. 1.666 − 619 =
2. 2.509 − 239 =
3. 3.389 − 298 =
4. 4.926 − 797 =
5. 5.774 − 198 =
6. 6.682 − 599 =
7. 7.699 − 459 =
8. 8.488 − 199 =
9. 9.971 − 428 =
10. 10.913 − 299 =
11. 11.408 − 198 =
12. 12.807 − 499 =
13. 13.702 − 498 =
14. 14.682 − 598 =
15. 15.560 − 497 =
16. 16.965 − 519 =
17. 17.427 − 408 =
18. 18.446 − 168 =
19. 19.942 − 199 =
20. 20.861 − 299 =
21. 21.416 − 299 =
22. 22.825 − 199 =
23. 23.543 − 117 =
24. 24.887 − 798 =
25. 25.624 − 199 =
26. 26.588 − 569 =
27. 27.879 − 799 =
28. 28.786 − 599 =
29. 29.754 − 398 =
30. 30.804 − 667 =
31. 31.957 − 397 =
32. 32.939 − 599 =
33. 33.972 − 199 =
34. 34.657 − 597 =
35. 35.776 − 699 =
36. 36.945 − 799 =
37. 37.858 − 249 =
38. 38.897 − 239 =
39. 39.950 − 798 =
40. 40.599 − 157 =

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