Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 566 · 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. 1.915 − 697 =
2. 2.875 − 799 =
3. 3.914 − 597 =
4. 4.899 − 588 =
5. 5.971 − 297 =
6. 6.698 − 318 =
7. 7.880 − 398 =
8. 8.816 − 797 =
9. 9.776 − 308 =
10. 10.514 − 297 =
11. 11.582 − 397 =
12. 12.387 − 198 =
13. 13.186 − 119 =
14. 14.883 − 798 =
15. 15.760 − 698 =
16. 16.370 − 219 =
17. 17.743 − 568 =
18. 18.988 − 799 =
19. 19.491 − 418 =
20. 20.659 − 597 =
21. 21.811 − 209 =
22. 22.747 − 299 =
23. 23.901 − 327 =
24. 24.792 − 597 =
25. 25.743 − 428 =
26. 26.525 − 309 =
27. 27.320 − 297 =
28. 28.670 − 617 =
29. 29.574 − 198 =
30. 30.978 − 397 =
31. 31.762 − 217 =
32. 32.940 − 698 =
33. 33.970 − 599 =
34. 34.493 − 297 =
35. 35.758 − 598 =
36. 36.676 − 408 =
37. 37.867 − 698 =
38. 38.994 − 798 =
39. 39.753 − 399 =
40. 40.573 − 119 =

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