Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 603 · 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. 1.845 − 177 =
2. 2.855 − 299 =
3. 3.917 − 599 =
4. 4.627 − 598 =
5. 5.310 − 198 =
6. 6.771 − 589 =
7. 7.437 − 398 =
8. 8.755 − 667 =
9. 9.872 − 299 =
10. 10.621 − 297 =
11. 11.397 − 248 =
12. 12.586 − 198 =
13. 13.793 − 499 =
14. 14.860 − 198 =
15. 15.704 − 529 =
16. 16.767 − 367 =
17. 17.664 − 368 =
18. 18.588 − 398 =
19. 19.921 − 798 =
20. 20.678 − 497 =
21. 21.839 − 798 =
22. 22.905 − 699 =
23. 23.753 − 599 =
24. 24.847 − 797 =
25. 25.343 − 299 =
26. 26.821 − 499 =
27. 27.832 − 299 =
28. 28.868 − 658 =
29. 29.722 − 437 =
30. 30.704 − 498 =
31. 31.954 − 607 =
32. 32.641 − 597 =
33. 33.958 − 699 =
34. 34.753 − 498 =
35. 35.948 − 198 =
36. 36.649 − 497 =
37. 37.741 − 499 =
38. 38.811 − 437 =
39. 39.755 − 597 =
40. 40.842 − 308 =

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