Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 106 · 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. 1.347 − 229 =
2. 2.834 − 399 =
3. 3.463 − 297 =
4. 4.672 − 399 =
5. 5.674 − 477 =
6. 6.905 − 458 =
7. 7.779 − 298 =
8. 8.473 − 199 =
9. 9.953 − 798 =
10. 10.907 − 497 =
11. 11.977 − 798 =
12. 12.429 − 297 =
13. 13.309 − 197 =
14. 14.742 − 319 =
15. 15.892 − 698 =
16. 16.995 − 599 =
17. 17.471 − 439 =
18. 18.950 − 638 =
19. 19.427 − 299 =
20. 20.327 − 287 =
21. 21.650 − 298 =
22. 22.417 − 329 =
23. 23.545 − 307 =
24. 24.948 − 197 =
25. 25.697 − 599 =
26. 26.513 − 397 =
27. 27.918 − 798 =
28. 28.618 − 499 =
29. 29.653 − 338 =
30. 30.971 − 668 =
31. 31.217 − 158 =
32. 32.718 − 427 =
33. 33.891 − 799 =
34. 34.767 − 399 =
35. 35.386 − 358 =
36. 36.579 − 399 =
37. 37.847 − 798 =
38. 38.626 − 579 =
39. 39.922 − 197 =
40. 40.873 − 799 =

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