Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 907 · 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. 1.751 − 227 =
2. 2.776 − 497 =
3. 3.896 − 798 =
4. 4.620 − 498 =
5. 5.906 − 797 =
6. 6.225 − 198 =
7. 7.766 − 699 =
8. 8.845 − 298 =
9. 9.887 − 439 =
10. 10.525 − 209 =
11. 11.862 − 499 =
12. 12.380 − 178 =
13. 13.839 − 499 =
14. 14.834 − 797 =
15. 15.448 − 249 =
16. 16.450 − 299 =
17. 17.839 − 798 =
18. 18.815 − 397 =
19. 19.765 − 197 =
20. 20.978 − 799 =
21. 21.959 − 449 =
22. 22.441 − 307 =
23. 23.875 − 547 =
24. 24.923 − 299 =
25. 25.663 − 568 =
26. 26.474 − 438 =
27. 27.714 − 348 =
28. 28.685 − 599 =
29. 29.830 − 499 =
30. 30.994 − 689 =
31. 31.925 − 799 =
32. 32.364 − 297 =
33. 33.921 − 299 =
34. 34.479 − 339 =
35. 35.720 − 299 =
36. 36.468 − 297 =
37. 37.975 − 298 =
38. 38.570 − 217 =
39. 39.939 − 499 =
40. 40.601 − 498 =

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