Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 803 · 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. 1.982 − 297 =
2. 2.950 − 317 =
3. 3.967 − 198 =
4. 4.833 − 649 =
5. 5.651 − 617 =
6. 6.796 − 479 =
7. 7.907 − 318 =
8. 8.837 − 399 =
9. 9.864 − 798 =
10. 10.436 − 299 =
11. 11.176 − 149 =
12. 12.836 − 697 =
13. 13.652 − 519 =
14. 14.886 − 199 =
15. 15.506 − 448 =
16. 16.475 − 329 =
17. 17.946 − 449 =
18. 18.716 − 287 =
19. 19.550 − 357 =
20. 20.977 − 497 =
21. 21.911 − 437 =
22. 22.718 − 297 =
23. 23.937 − 498 =
24. 24.319 − 198 =
25. 25.949 − 698 =
26. 26.841 − 498 =
27. 27.485 − 197 =
28. 28.763 − 397 =
29. 29.767 − 157 =
30. 30.355 − 198 =
31. 31.628 − 157 =
32. 32.684 − 397 =
33. 33.923 − 199 =
34. 34.872 − 598 =
35. 35.950 − 197 =
36. 36.594 − 199 =
37. 37.330 − 157 =
38. 38.879 − 327 =
39. 39.913 − 597 =
40. 40.502 − 338 =

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