Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 283 · 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. 1.905 − 477 =
2. 2.776 − 537 =
3. 3.525 − 368 =
4. 4.818 − 497 =
5. 5.716 − 398 =
6. 6.728 − 169 =
7. 7.425 − 197 =
8. 8.960 − 489 =
9. 9.720 − 588 =
10. 10.917 − 698 =
11. 11.778 − 669 =
12. 12.575 − 117 =
13. 13.766 − 307 =
14. 14.308 − 198 =
15. 15.394 − 197 =
16. 16.820 − 498 =
17. 17.816 − 499 =
18. 18.736 − 599 =
19. 19.723 − 599 =
20. 20.318 − 297 =
21. 21.691 − 208 =
22. 22.340 − 289 =
23. 23.957 − 509 =
24. 24.902 − 199 =
25. 25.768 − 659 =
26. 26.865 − 497 =
27. 27.623 − 297 =
28. 28.468 − 147 =
29. 29.859 − 797 =
30. 30.531 − 399 =
31. 31.479 − 298 =
32. 32.878 − 238 =
33. 33.359 − 278 =
34. 34.722 − 399 =
35. 35.911 − 517 =
36. 36.945 − 397 =
37. 37.721 − 198 =
38. 38.811 − 298 =
39. 39.534 − 197 =
40. 40.355 − 199 =

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