Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 908 · 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. 1.505 − 408 =
2. 2.901 − 599 =
3. 3.433 − 199 =
4. 4.238 − 158 =
5. 5.936 − 697 =
6. 6.957 − 397 =
7. 7.904 − 509 =
8. 8.590 − 508 =
9. 9.533 − 199 =
10. 10.811 − 618 =
11. 11.831 − 637 =
12. 12.565 − 317 =
13. 13.942 − 799 =
14. 14.716 − 697 =
15. 15.529 − 399 =
16. 16.597 − 199 =
17. 17.762 − 188 =
18. 18.838 − 399 =
19. 19.715 − 579 =
20. 20.750 − 187 =
21. 21.908 − 697 =
22. 22.896 − 697 =
23. 23.783 − 277 =
24. 24.585 − 199 =
25. 25.873 − 799 =
26. 26.883 − 647 =
27. 27.603 − 358 =
28. 28.841 − 659 =
29. 29.897 − 299 =
30. 30.734 − 299 =
31. 31.936 − 797 =
32. 32.512 − 198 =
33. 33.665 − 408 =
34. 34.799 − 658 =
35. 35.444 − 207 =
36. 36.682 − 637 =
37. 37.771 − 159 =
38. 38.894 − 698 =
39. 39.717 − 397 =
40. 40.953 − 658 =

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