Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 835 · 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. 1.791 − 397 =
2. 2.813 − 497 =
3. 3.837 − 597 =
4. 4.612 − 398 =
5. 5.638 − 197 =
6. 6.808 − 499 =
7. 7.820 − 399 =
8. 8.775 − 298 =
9. 9.914 − 159 =
10. 10.867 − 238 =
11. 11.981 − 628 =
12. 12.329 − 298 =
13. 13.694 − 499 =
14. 14.742 − 597 =
15. 15.335 − 197 =
16. 16.781 − 398 =
17. 17.665 − 528 =
18. 18.885 − 197 =
19. 19.338 − 299 =
20. 20.986 − 439 =
21. 21.304 − 249 =
22. 22.596 − 399 =
23. 23.869 − 799 =
24. 24.999 − 688 =
25. 25.672 − 349 =
26. 26.992 − 599 =
27. 27.522 − 498 =
28. 28.438 − 419 =
29. 29.388 − 328 =
30. 30.688 − 498 =
31. 31.819 − 438 =
32. 32.446 − 367 =
33. 33.879 − 798 =
34. 34.305 − 287 =
35. 35.796 − 699 =
36. 36.973 − 607 =
37. 37.752 − 179 =
38. 38.363 − 199 =
39. 39.843 − 197 =
40. 40.353 − 299 =

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