Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 727 · 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. 1.769 − 688 =
2. 2.413 − 128 =
3. 3.455 − 299 =
4. 4.553 − 299 =
5. 5.321 − 299 =
6. 6.750 − 299 =
7. 7.817 − 597 =
8. 8.699 − 398 =
9. 9.898 − 577 =
10. 10.677 − 629 =
11. 11.722 − 648 =
12. 12.894 − 458 =
13. 13.640 − 237 =
14. 14.945 − 799 =
15. 15.739 − 208 =
16. 16.443 − 198 =
17. 17.412 − 368 =
18. 18.917 − 699 =
19. 19.767 − 199 =
20. 20.555 − 398 =
21. 21.640 − 499 =
22. 22.446 − 159 =
23. 23.773 − 399 =
24. 24.687 − 277 =
25. 25.319 − 298 =
26. 26.892 − 497 =
27. 27.998 − 297 =
28. 28.836 − 667 =
29. 29.903 − 519 =
30. 30.776 − 297 =
31. 31.495 − 148 =
32. 32.522 − 498 =
33. 33.948 − 797 =
34. 34.795 − 499 =
35. 35.899 − 127 =
36. 36.377 − 269 =
37. 37.647 − 198 =
38. 38.552 − 359 =
39. 39.893 − 488 =
40. 40.244 − 118 =

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