Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 97 · 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. 1.775 − 169 =
2. 2.481 − 297 =
3. 3.966 − 699 =
4. 4.680 − 398 =
5. 5.626 − 458 =
6. 6.663 − 299 =
7. 7.444 − 199 =
8. 8.815 − 699 =
9. 9.684 − 557 =
10. 10.523 − 299 =
11. 11.825 − 699 =
12. 12.855 − 559 =
13. 13.815 − 629 =
14. 14.277 − 197 =
15. 15.974 − 399 =
16. 16.916 − 528 =
17. 17.865 − 237 =
18. 18.877 − 798 =
19. 19.694 − 199 =
20. 20.930 − 218 =
21. 21.820 − 658 =
22. 22.357 − 298 =
23. 23.508 − 398 =
24. 24.734 − 199 =
25. 25.870 − 599 =
26. 26.954 − 798 =
27. 27.822 − 497 =
28. 28.809 − 499 =
29. 29.634 − 599 =
30. 30.345 − 299 =
31. 31.807 − 397 =
32. 32.727 − 697 =
33. 33.650 − 219 =
34. 34.903 − 647 =
35. 35.479 − 399 =
36. 36.806 − 398 =
37. 37.805 − 497 =
38. 38.744 − 199 =
39. 39.627 − 498 =
40. 40.851 − 648 =

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