Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 785 · 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. 1.677 − 349 =
2. 2.530 − 427 =
3. 3.414 − 399 =
4. 4.758 − 589 =
5. 5.490 − 298 =
6. 6.642 − 599 =
7. 7.668 − 198 =
8. 8.999 − 597 =
9. 9.652 − 599 =
10. 10.982 − 699 =
11. 11.886 − 297 =
12. 12.779 − 367 =
13. 13.590 − 399 =
14. 14.630 − 397 =
15. 15.490 − 398 =
16. 16.319 − 228 =
17. 17.643 − 279 =
18. 18.804 − 587 =
19. 19.765 − 698 =
20. 20.328 − 247 =
21. 21.368 − 319 =
22. 22.728 − 599 =
23. 23.764 − 598 =
24. 24.863 − 597 =
25. 25.880 − 499 =
26. 26.897 − 797 =
27. 27.812 − 498 =
28. 28.871 − 699 =
29. 29.694 − 498 =
30. 30.897 − 309 =
31. 31.736 − 619 =
32. 32.777 − 648 =
33. 33.825 − 597 =
34. 34.795 − 697 =
35. 35.945 − 599 =
36. 36.715 − 499 =
37. 37.698 − 338 =
38. 38.703 − 688 =
39. 39.906 − 148 =
40. 40.677 − 197 =

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