Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 450 · 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. 1.957 − 509 =
2. 2.317 − 228 =
3. 3.747 − 599 =
4. 4.781 − 297 =
5. 5.928 − 299 =
6. 6.752 − 489 =
7. 7.928 − 697 =
8. 8.918 − 699 =
9. 9.357 − 169 =
10. 10.736 − 219 =
11. 11.843 − 699 =
12. 12.656 − 599 =
13. 13.962 − 597 =
14. 14.655 − 197 =
15. 15.925 − 599 =
16. 16.478 − 129 =
17. 17.721 − 698 =
18. 18.737 − 398 =
19. 19.459 − 438 =
20. 20.838 − 249 =
21. 21.806 − 408 =
22. 22.453 − 199 =
23. 23.441 − 399 =
24. 24.481 − 199 =
25. 25.799 − 247 =
26. 26.604 − 529 =
27. 27.919 − 599 =
28. 28.580 − 157 =
29. 29.859 − 698 =
30. 30.439 − 399 =
31. 31.965 − 199 =
32. 32.764 − 598 =
33. 33.706 − 299 =
34. 34.889 − 198 =
35. 35.402 − 277 =
36. 36.915 − 199 =
37. 37.779 − 407 =
38. 38.538 − 127 =
39. 39.964 − 599 =
40. 40.445 − 298 =

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