Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 243 · 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. 1.821 − 799 =
2. 2.779 − 197 =
3. 3.878 − 369 =
4. 4.849 − 499 =
5. 5.940 − 669 =
6. 6.998 − 197 =
7. 7.596 − 419 =
8. 8.335 − 197 =
9. 9.691 − 459 =
10. 10.811 − 198 =
11. 11.555 − 497 =
12. 12.938 − 557 =
13. 13.181 − 127 =
14. 14.921 − 498 =
15. 15.831 − 299 =
16. 16.909 − 599 =
17. 17.909 − 199 =
18. 18.589 − 429 =
19. 19.956 − 798 =
20. 20.436 − 298 =
21. 21.782 − 588 =
22. 22.880 − 799 =
23. 23.500 − 398 =
24. 24.685 − 599 =
25. 25.958 − 379 =
26. 26.612 − 299 =
27. 27.821 − 797 =
28. 28.474 − 198 =
29. 29.994 − 497 =
30. 30.934 − 147 =
31. 31.606 − 498 =
32. 32.649 − 549 =
33. 33.673 − 498 =
34. 34.814 − 797 =
35. 35.936 − 599 =
36. 36.515 − 479 =
37. 37.741 − 308 =
38. 38.471 − 399 =
39. 39.816 − 297 =
40. 40.809 − 379 =

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