Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 391 · 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. 1.745 − 468 =
2. 2.890 − 128 =
3. 3.491 − 199 =
4. 4.494 − 239 =
5. 5.248 − 197 =
6. 6.899 − 597 =
7. 7.861 − 518 =
8. 8.850 − 477 =
9. 9.920 − 299 =
10. 10.566 − 399 =
11. 11.999 − 399 =
12. 12.750 − 199 =
13. 13.617 − 198 =
14. 14.773 − 697 =
15. 15.971 − 798 =
16. 16.274 − 128 =
17. 17.559 − 539 =
18. 18.457 − 158 =
19. 19.653 − 499 =
20. 20.869 − 399 =
21. 21.943 − 629 =
22. 22.376 − 189 =
23. 23.963 − 628 =
24. 24.707 − 267 =
25. 25.755 − 559 =
26. 26.600 − 298 =
27. 27.744 − 599 =
28. 28.855 − 797 =
29. 29.243 − 169 =
30. 30.885 − 697 =
31. 31.628 − 577 =
32. 32.688 − 188 =
33. 33.464 − 298 =
34. 34.964 − 598 =
35. 35.969 − 599 =
36. 36.528 − 409 =
37. 37.214 − 118 =
38. 38.374 − 259 =
39. 39.494 − 299 =
40. 40.743 − 699 =

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