Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 439 · 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. 1.675 − 619 =
2. 2.997 − 797 =
3. 3.513 − 199 =
4. 4.760 − 269 =
5. 5.521 − 398 =
6. 6.789 − 659 =
7. 7.745 − 397 =
8. 8.324 − 159 =
9. 9.804 − 298 =
10. 10.596 − 299 =
11. 11.939 − 699 =
12. 12.833 − 599 =
13. 13.591 − 478 =
14. 14.837 − 499 =
15. 15.543 − 237 =
16. 16.723 − 198 =
17. 17.983 − 698 =
18. 18.731 − 287 =
19. 19.853 − 458 =
20. 20.532 − 198 =
21. 21.884 − 497 =
22. 22.791 − 297 =
23. 23.915 − 328 =
24. 24.547 − 399 =
25. 25.969 − 699 =
26. 26.643 − 518 =
27. 27.680 − 188 =
28. 28.605 − 399 =
29. 29.377 − 189 =
30. 30.318 − 199 =
31. 31.940 − 298 =
32. 32.450 − 398 =
33. 33.287 − 177 =
34. 34.794 − 238 =
35. 35.335 − 297 =
36. 36.393 − 298 =
37. 37.864 − 799 =
38. 38.836 − 499 =
39. 39.864 − 469 =
40. 40.767 − 697 =

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