Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 545 · 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. 1.981 − 398 =
2. 2.871 − 389 =
3. 3.893 − 197 =
4. 4.592 − 498 =
5. 5.762 − 278 =
6. 6.716 − 639 =
7. 7.566 − 297 =
8. 8.613 − 398 =
9. 9.963 − 599 =
10. 10.404 − 269 =
11. 11.604 − 348 =
12. 12.409 − 297 =
13. 13.893 − 497 =
14. 14.603 − 327 =
15. 15.977 − 679 =
16. 16.826 − 297 =
17. 17.560 − 239 =
18. 18.627 − 498 =
19. 19.475 − 397 =
20. 20.708 − 149 =
21. 21.245 − 199 =
22. 22.615 − 167 =
23. 23.562 − 397 =
24. 24.452 − 398 =
25. 25.782 − 497 =
26. 26.811 − 397 =
27. 27.871 − 598 =
28. 28.884 − 348 =
29. 29.979 − 298 =
30. 30.571 − 209 =
31. 31.581 − 399 =
32. 32.506 − 318 =
33. 33.469 − 398 =
34. 34.986 − 798 =
35. 35.960 − 698 =
36. 36.862 − 497 =
37. 37.909 − 698 =
38. 38.269 − 199 =
39. 39.282 − 197 =
40. 40.719 − 277 =

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