Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 190 · 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. 1.663 − 598 =
2. 2.630 − 447 =
3. 3.348 − 117 =
4. 4.776 − 519 =
5. 5.609 − 399 =
6. 6.698 − 339 =
7. 7.810 − 597 =
8. 8.916 − 378 =
9. 9.669 − 367 =
10. 10.925 − 499 =
11. 11.792 − 598 =
12. 12.945 − 199 =
13. 13.859 − 408 =
14. 14.858 − 169 =
15. 15.755 − 598 =
16. 16.595 − 299 =
17. 17.954 − 269 =
18. 18.673 − 307 =
19. 19.859 − 337 =
20. 20.855 − 698 =
21. 21.721 − 659 =
22. 22.749 − 277 =
23. 23.383 − 199 =
24. 24.582 − 249 =
25. 25.428 − 269 =
26. 26.969 − 508 =
27. 27.868 − 797 =
28. 28.802 − 628 =
29. 29.608 − 239 =
30. 30.679 − 588 =
31. 31.174 − 119 =
32. 32.604 − 497 =
33. 33.927 − 578 =
34. 34.832 − 398 =
35. 35.924 − 447 =
36. 36.850 − 397 =
37. 37.632 − 398 =
38. 38.976 − 398 =
39. 39.753 − 599 =
40. 40.405 − 197 =

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