Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 705 · 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. 1.421 − 128 =
2. 2.258 − 199 =
3. 3.713 − 127 =
4. 4.881 − 479 =
5. 5.630 − 299 =
6. 6.422 − 378 =
7. 7.397 − 298 =
8. 8.829 − 458 =
9. 9.696 − 199 =
10. 10.453 − 419 =
11. 11.795 − 687 =
12. 12.699 − 499 =
13. 13.841 − 797 =
14. 14.905 − 399 =
15. 15.879 − 248 =
16. 16.340 − 297 =
17. 17.335 − 299 =
18. 18.854 − 347 =
19. 19.280 − 179 =
20. 20.963 − 318 =
21. 21.649 − 298 =
22. 22.468 − 397 =
23. 23.698 − 149 =
24. 24.609 − 589 =
25. 25.755 − 399 =
26. 26.771 − 657 =
27. 27.890 − 599 =
28. 28.456 − 299 =
29. 29.366 − 198 =
30. 30.359 − 127 =
31. 31.341 − 307 =
32. 32.774 − 398 =
33. 33.643 − 447 =
34. 34.720 − 497 =
35. 35.427 − 298 =
36. 36.871 − 697 =
37. 37.835 − 797 =
38. 38.437 − 188 =
39. 39.752 − 319 =
40. 40.375 − 299 =

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