Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 182 · 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. 1.435 − 299 =
2. 2.464 − 397 =
3. 3.997 − 398 =
4. 4.680 − 199 =
5. 5.841 − 698 =
6. 6.664 − 288 =
7. 7.614 − 218 =
8. 8.986 − 598 =
9. 9.731 − 498 =
10. 10.994 − 609 =
11. 11.984 − 118 =
12. 12.678 − 658 =
13. 13.926 − 538 =
14. 14.914 − 199 =
15. 15.358 − 287 =
16. 16.849 − 797 =
17. 17.949 − 599 =
18. 18.357 − 148 =
19. 19.892 − 599 =
20. 20.523 − 479 =
21. 21.868 − 697 =
22. 22.861 − 798 =
23. 23.788 − 688 =
24. 24.816 − 799 =
25. 25.366 − 199 =
26. 26.900 − 798 =
27. 27.478 − 199 =
28. 28.783 − 199 =
29. 29.668 − 639 =
30. 30.972 − 149 =
31. 31.400 − 297 =
32. 32.936 − 498 =
33. 33.706 − 358 =
34. 34.983 − 598 =
35. 35.993 − 798 =
36. 36.815 − 798 =
37. 37.894 − 699 =
38. 38.649 − 599 =
39. 39.805 − 467 =
40. 40.745 − 698 =

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