Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 726 · 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. 1.736 − 688 =
2. 2.686 − 557 =
3. 3.836 − 517 =
4. 4.573 − 397 =
5. 5.458 − 397 =
6. 6.814 − 617 =
7. 7.643 − 267 =
8. 8.700 − 197 =
9. 9.978 − 298 =
10. 10.718 − 599 =
11. 11.988 − 648 =
12. 12.673 − 299 =
13. 13.855 − 697 =
14. 14.687 − 428 =
15. 15.926 − 657 =
16. 16.846 − 697 =
17. 17.737 − 678 =
18. 18.777 − 698 =
19. 19.901 − 699 =
20. 20.470 − 397 =
21. 21.950 − 799 =
22. 22.646 − 138 =
23. 23.846 − 699 =
24. 24.907 − 478 =
25. 25.908 − 297 =
26. 26.758 − 389 =
27. 27.615 − 397 =
28. 28.914 − 598 =
29. 29.652 − 399 =
30. 30.717 − 398 =
31. 31.831 − 379 =
32. 32.843 − 657 =
33. 33.955 − 699 =
34. 34.955 − 198 =
35. 35.941 − 399 =
36. 36.982 − 519 =
37. 37.991 − 178 =
38. 38.913 − 599 =
39. 39.790 − 678 =
40. 40.940 − 327 =

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