Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 348 · 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. 1.984 − 607 =
2. 2.673 − 499 =
3. 3.478 − 339 =
4. 4.882 − 299 =
5. 5.765 − 399 =
6. 6.865 − 558 =
7. 7.910 − 138 =
8. 8.322 − 297 =
9. 9.489 − 199 =
10. 10.336 − 198 =
11. 11.614 − 177 =
12. 12.735 − 199 =
13. 13.700 − 347 =
14. 14.992 − 199 =
15. 15.516 − 399 =
16. 16.686 − 199 =
17. 17.888 − 508 =
18. 18.808 − 658 =
19. 19.614 − 119 =
20. 20.664 − 508 =
21. 21.962 − 197 =
22. 22.506 − 398 =
23. 23.599 − 519 =
24. 24.723 − 499 =
25. 25.503 − 297 =
26. 26.363 − 298 =
27. 27.747 − 277 =
28. 28.827 − 567 =
29. 29.880 − 348 =
30. 30.991 − 699 =
31. 31.935 − 699 =
32. 32.882 − 199 =
33. 33.667 − 527 =
34. 34.545 − 398 =
35. 35.697 − 348 =
36. 36.785 − 679 =
37. 37.711 − 499 =
38. 38.990 − 668 =
39. 39.373 − 249 =
40. 40.527 − 397 =

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