Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 213 · 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. 1.586 − 297 =
2. 2.937 − 617 =
3. 3.910 − 699 =
4. 4.335 − 198 =
5. 5.964 − 439 =
6. 6.972 − 597 =
7. 7.435 − 358 =
8. 8.969 − 199 =
9. 9.876 − 598 =
10. 10.907 − 797 =
11. 11.984 − 198 =
12. 12.816 − 398 =
13. 13.473 − 398 =
14. 14.276 − 167 =
15. 15.729 − 199 =
16. 16.672 − 457 =
17. 17.933 − 799 =
18. 18.857 − 189 =
19. 19.578 − 247 =
20. 20.752 − 237 =
21. 21.357 − 167 =
22. 22.949 − 197 =
23. 23.595 − 148 =
24. 24.645 − 297 =
25. 25.814 − 599 =
26. 26.512 − 299 =
27. 27.919 − 697 =
28. 28.907 − 239 =
29. 29.610 − 279 =
30. 30.489 − 349 =
31. 31.625 − 299 =
32. 32.963 − 438 =
33. 33.919 − 139 =
34. 34.770 − 118 =
35. 35.638 − 537 =
36. 36.833 − 578 =
37. 37.234 − 197 =
38. 38.878 − 589 =
39. 39.371 − 199 =
40. 40.622 − 397 =

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