Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 978 · 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. 1.574 − 397 =
2. 2.635 − 329 =
3. 3.989 − 388 =
4. 4.955 − 798 =
5. 5.586 − 568 =
6. 6.916 − 598 =
7. 7.718 − 399 =
8. 8.668 − 548 =
9. 9.707 − 398 =
10. 10.935 − 597 =
11. 11.753 − 599 =
12. 12.704 − 277 =
13. 13.760 − 359 =
14. 14.784 − 198 =
15. 15.837 − 497 =
16. 16.435 − 299 =
17. 17.580 − 478 =
18. 18.732 − 628 =
19. 19.376 − 177 =
20. 20.479 − 398 =
21. 21.837 − 529 =
22. 22.472 − 298 =
23. 23.936 − 699 =
24. 24.830 − 497 =
25. 25.986 − 799 =
26. 26.932 − 499 =
27. 27.393 − 268 =
28. 28.716 − 318 =
29. 29.506 − 287 =
30. 30.618 − 597 =
31. 31.393 − 197 =
32. 32.437 − 198 =
33. 33.908 − 198 =
34. 34.954 − 367 =
35. 35.689 − 198 =
36. 36.912 − 399 =
37. 37.466 − 159 =
38. 38.546 − 397 =
39. 39.548 − 199 =
40. 40.724 − 499 =

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