Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 612 · 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. 1.482 − 309 =
2. 2.836 − 298 =
3. 3.465 − 397 =
4. 4.849 − 297 =
5. 5.682 − 299 =
6. 6.971 − 498 =
7. 7.727 − 608 =
8. 8.668 − 489 =
9. 9.914 − 149 =
10. 10.737 − 299 =
11. 11.977 − 607 =
12. 12.673 − 289 =
13. 13.699 − 469 =
14. 14.964 − 687 =
15. 15.301 − 148 =
16. 16.587 − 499 =
17. 17.888 − 799 =
18. 18.925 − 209 =
19. 19.902 − 577 =
20. 20.866 − 697 =
21. 21.880 − 799 =
22. 22.947 − 249 =
23. 23.599 − 509 =
24. 24.914 − 397 =
25. 25.967 − 698 =
26. 26.882 − 198 =
27. 27.723 − 189 =
28. 28.332 − 198 =
29. 29.884 − 799 =
30. 30.608 − 299 =
31. 31.428 − 408 =
32. 32.924 − 399 =
33. 33.950 − 207 =
34. 34.643 − 397 =
35. 35.620 − 498 =
36. 36.629 − 509 =
37. 37.861 − 267 =
38. 38.484 − 399 =
39. 39.767 − 659 =
40. 40.648 − 558 =

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