Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 505 · 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. 1.689 − 397 =
2. 2.586 − 449 =
3. 3.488 − 139 =
4. 4.691 − 498 =
5. 5.823 − 699 =
6. 6.608 − 508 =
7. 7.974 − 798 =
8. 8.832 − 598 =
9. 9.760 − 667 =
10. 10.854 − 199 =
11. 11.653 − 199 =
12. 12.268 − 198 =
13. 13.853 − 798 =
14. 14.489 − 239 =
15. 15.536 − 268 =
16. 16.719 − 517 =
17. 17.268 − 138 =
18. 18.861 − 799 =
19. 19.881 − 798 =
20. 20.777 − 698 =
21. 21.557 − 397 =
22. 22.769 − 299 =
23. 23.680 − 598 =
24. 24.541 − 298 =
25. 25.834 − 597 =
26. 26.910 − 697 =
27. 27.878 − 599 =
28. 28.628 − 499 =
29. 29.820 − 699 =
30. 30.703 − 539 =
31. 31.514 − 399 =
32. 32.950 − 377 =
33. 33.833 − 798 =
34. 34.949 − 699 =
35. 35.519 − 198 =
36. 36.602 − 559 =
37. 37.897 − 598 =
38. 38.896 − 498 =
39. 39.831 − 297 =
40. 40.883 − 499 =

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