Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 823 · 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. 1.832 − 137 =
2. 2.669 − 299 =
3. 3.597 − 399 =
4. 4.866 − 377 =
5. 5.495 − 397 =
6. 6.780 − 568 =
7. 7.682 − 198 =
8. 8.400 − 157 =
9. 9.854 − 699 =
10. 10.867 − 427 =
11. 11.263 − 189 =
12. 12.786 − 699 =
13. 13.698 − 388 =
14. 14.766 − 397 =
15. 15.986 − 699 =
16. 16.960 − 699 =
17. 17.753 − 398 =
18. 18.654 − 599 =
19. 19.537 − 428 =
20. 20.671 − 317 =
21. 21.652 − 198 =
22. 22.613 − 539 =
23. 23.870 − 798 =
24. 24.419 − 199 =
25. 25.913 − 699 =
26. 26.749 − 219 =
27. 27.441 − 198 =
28. 28.669 − 428 =
29. 29.258 − 237 =
30. 30.421 − 318 =
31. 31.830 − 248 =
32. 32.879 − 148 =
33. 33.856 − 267 =
34. 34.716 − 417 =
35. 35.731 − 598 =
36. 36.750 − 599 =
37. 37.737 − 578 =
38. 38.291 − 217 =
39. 39.773 − 347 =
40. 40.603 − 258 =

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