Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 859 · 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. 1.460 − 299 =
2. 2.707 − 399 =
3. 3.689 − 169 =
4. 4.521 − 257 =
5. 5.342 − 317 =
6. 6.462 − 297 =
7. 7.359 − 149 =
8. 8.957 − 597 =
9. 9.325 − 269 =
10. 10.880 − 697 =
11. 11.664 − 599 =
12. 12.694 − 398 =
13. 13.703 − 397 =
14. 14.983 − 697 =
15. 15.510 − 347 =
16. 16.548 − 468 =
17. 17.365 − 349 =
18. 18.217 − 129 =
19. 19.928 − 588 =
20. 20.817 − 197 =
21. 21.416 − 228 =
22. 22.484 − 197 =
23. 23.972 − 698 =
24. 24.950 − 208 =
25. 25.909 − 297 =
26. 26.923 − 698 =
27. 27.468 − 199 =
28. 28.986 − 397 =
29. 29.524 − 299 =
30. 30.756 − 207 =
31. 31.806 − 598 =
32. 32.900 − 599 =
33. 33.717 − 698 =
34. 34.789 − 258 =
35. 35.912 − 299 =
36. 36.596 − 398 =
37. 37.393 − 198 =
38. 38.767 − 398 =
39. 39.762 − 599 =
40. 40.845 − 488 =

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