Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 136 · 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. 1.388 − 258 =
2. 2.812 − 279 =
3. 3.895 − 597 =
4. 4.460 − 378 =
5. 5.398 − 348 =
6. 6.548 − 269 =
7. 7.764 − 427 =
8. 8.840 − 298 =
9. 9.839 − 548 =
10. 10.743 − 489 =
11. 11.406 − 299 =
12. 12.634 − 398 =
13. 13.374 − 299 =
14. 14.473 − 319 =
15. 15.965 − 599 =
16. 16.939 − 698 =
17. 17.680 − 298 =
18. 18.907 − 299 =
19. 19.859 − 399 =
20. 20.953 − 199 =
21. 21.334 − 198 =
22. 22.856 − 798 =
23. 23.777 − 267 =
24. 24.840 − 149 =
25. 25.935 − 639 =
26. 26.940 − 428 =
27. 27.993 − 687 =
28. 28.998 − 497 =
29. 29.882 − 799 =
30. 30.683 − 559 =
31. 31.836 − 197 =
32. 32.650 − 127 =
33. 33.822 − 798 =
34. 34.538 − 199 =
35. 35.913 − 399 =
36. 36.851 − 487 =
37. 37.222 − 199 =
38. 38.900 − 497 =
39. 39.637 − 427 =
40. 40.528 − 497 =

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