Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 760 · 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. 1.704 − 479 =
2. 2.681 − 197 =
3. 3.457 − 399 =
4. 4.278 − 207 =
5. 5.387 − 237 =
6. 6.815 − 257 =
7. 7.713 − 558 =
8. 8.786 − 599 =
9. 9.866 − 397 =
10. 10.788 − 198 =
11. 11.962 − 197 =
12. 12.703 − 598 =
13. 13.949 − 498 =
14. 14.645 − 398 =
15. 15.531 − 338 =
16. 16.651 − 597 =
17. 17.495 − 429 =
18. 18.338 − 298 =
19. 19.577 − 558 =
20. 20.943 − 298 =
21. 21.681 − 599 =
22. 22.935 − 499 =
23. 23.362 − 299 =
24. 24.413 − 259 =
25. 25.855 − 497 =
26. 26.643 − 519 =
27. 27.900 − 499 =
28. 28.433 − 309 =
29. 29.962 − 298 =
30. 30.519 − 199 =
31. 31.229 − 208 =
32. 32.446 − 399 =
33. 33.884 − 798 =
34. 34.717 − 597 =
35. 35.983 − 537 =
36. 36.617 − 299 =
37. 37.844 − 399 =
38. 38.931 − 597 =
39. 39.575 − 499 =
40. 40.531 − 177 =

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