Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 977 · 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. 1.828 − 699 =
2. 2.972 − 599 =
3. 3.542 − 349 =
4. 4.463 − 218 =
5. 5.828 − 697 =
6. 6.905 − 639 =
7. 7.973 − 399 =
8. 8.585 − 398 =
9. 9.883 − 798 =
10. 10.641 − 597 =
11. 11.877 − 448 =
12. 12.778 − 397 =
13. 13.828 − 797 =
14. 14.932 − 598 =
15. 15.563 − 497 =
16. 16.222 − 199 =
17. 17.671 − 318 =
18. 18.657 − 597 =
19. 19.822 − 599 =
20. 20.964 − 699 =
21. 21.839 − 598 =
22. 22.960 − 648 =
23. 23.462 − 219 =
24. 24.947 − 197 =
25. 25.770 − 287 =
26. 26.202 − 147 =
27. 27.985 − 797 =
28. 28.985 − 598 =
29. 29.521 − 398 =
30. 30.830 − 597 =
31. 31.440 − 297 =
32. 32.436 − 398 =
33. 33.922 − 508 =
34. 34.926 − 259 =
35. 35.771 − 199 =
36. 36.848 − 798 =
37. 37.415 − 137 =
38. 38.530 − 297 =
39. 39.845 − 797 =
40. 40.417 − 197 =

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