Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 232 · 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. 1.734 − 478 =
2. 2.572 − 149 =
3. 3.990 − 497 =
4. 4.695 − 609 =
5. 5.763 − 479 =
6. 6.783 − 599 =
7. 7.707 − 398 =
8. 8.914 − 697 =
9. 9.302 − 198 =
10. 10.681 − 297 =
11. 11.623 − 608 =
12. 12.809 − 397 =
13. 13.901 − 699 =
14. 14.901 − 497 =
15. 15.356 − 198 =
16. 16.893 − 798 =
17. 17.954 − 508 =
18. 18.585 − 298 =
19. 19.326 − 299 =
20. 20.675 − 217 =
21. 21.746 − 497 =
22. 22.620 − 597 =
23. 23.685 − 299 =
24. 24.480 − 299 =
25. 25.446 − 148 =
26. 26.625 − 398 =
27. 27.751 − 698 =
28. 28.968 − 198 =
29. 29.319 − 297 =
30. 30.652 − 199 =
31. 31.472 − 368 =
32. 32.925 − 797 =
33. 33.877 − 599 =
34. 34.861 − 797 =
35. 35.795 − 597 =
36. 36.978 − 698 =
37. 37.352 − 198 =
38. 38.746 − 288 =
39. 39.765 − 698 =
40. 40.942 − 587 =

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