Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 707 · 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. 1.800 − 699 =
2. 2.816 − 298 =
3. 3.696 − 498 =
4. 4.433 − 378 =
5. 5.773 − 697 =
6. 6.671 − 358 =
7. 7.841 − 699 =
8. 8.470 − 247 =
9. 9.346 − 318 =
10. 10.879 − 329 =
11. 11.785 − 597 =
12. 12.332 − 198 =
13. 13.796 − 389 =
14. 14.580 − 489 =
15. 15.862 − 308 =
16. 16.296 − 228 =
17. 17.737 − 697 =
18. 18.768 − 259 =
19. 19.181 − 157 =
20. 20.348 − 299 =
21. 21.812 − 447 =
22. 22.654 − 198 =
23. 23.782 − 699 =
24. 24.883 − 667 =
25. 25.366 − 197 =
26. 26.976 − 797 =
27. 27.212 − 159 =
28. 28.667 − 597 =
29. 29.981 − 569 =
30. 30.673 − 437 =
31. 31.718 − 599 =
32. 32.811 − 377 =
33. 33.622 − 498 =
34. 34.995 − 438 =
35. 35.650 − 298 =
36. 36.833 − 488 =
37. 37.797 − 699 =
38. 38.888 − 189 =
39. 39.421 − 189 =
40. 40.447 − 358 =

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