Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 146 · 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. 1.580 − 437 =
2. 2.678 − 407 =
3. 3.643 − 617 =
4. 4.901 − 699 =
5. 5.884 − 297 =
6. 6.938 − 798 =
7. 7.390 − 249 =
8. 8.987 − 427 =
9. 9.502 − 399 =
10. 10.789 − 198 =
11. 11.625 − 547 =
12. 12.668 − 599 =
13. 13.983 − 199 =
14. 14.533 − 398 =
15. 15.697 − 408 =
16. 16.861 − 498 =
17. 17.445 − 399 =
18. 18.833 − 799 =
19. 19.653 − 399 =
20. 20.777 − 538 =
21. 21.657 − 399 =
22. 22.744 − 259 =
23. 23.772 − 298 =
24. 24.755 − 498 =
25. 25.903 − 619 =
26. 26.381 − 299 =
27. 27.567 − 479 =
28. 28.601 − 327 =
29. 29.968 − 239 =
30. 30.531 − 297 =
31. 31.700 − 499 =
32. 32.558 − 199 =
33. 33.750 − 499 =
34. 34.292 − 198 =
35. 35.957 − 797 =
36. 36.385 − 199 =
37. 37.739 − 199 =
38. 38.776 − 499 =
39. 39.652 − 287 =
40. 40.704 − 517 =

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