Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 607 · 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. 1.680 − 479 =
2. 2.815 − 378 =
3. 3.919 − 799 =
4. 4.333 − 199 =
5. 5.297 − 259 =
6. 6.373 − 198 =
7. 7.919 − 699 =
8. 8.772 − 697 =
9. 9.590 − 198 =
10. 10.672 − 588 =
11. 11.967 − 458 =
12. 12.891 − 298 =
13. 13.595 − 277 =
14. 14.922 − 799 =
15. 15.621 − 168 =
16. 16.239 − 197 =
17. 17.674 − 207 =
18. 18.294 − 199 =
19. 19.250 − 219 =
20. 20.539 − 298 =
21. 21.895 − 797 =
22. 22.971 − 799 =
23. 23.896 − 697 =
24. 24.889 − 798 =
25. 25.850 − 799 =
26. 26.894 − 697 =
27. 27.566 − 297 =
28. 28.939 − 798 =
29. 29.990 − 627 =
30. 30.705 − 248 =
31. 31.896 − 278 =
32. 32.899 − 298 =
33. 33.901 − 387 =
34. 34.819 − 697 =
35. 35.792 − 699 =
36. 36.706 − 497 =
37. 37.983 − 599 =
38. 38.843 − 698 =
39. 39.868 − 597 =
40. 40.725 − 699 =

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