Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 491 · 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. 1.899 − 309 =
2. 2.649 − 398 =
3. 3.535 − 499 =
4. 4.767 − 409 =
5. 5.894 − 297 =
6. 6.652 − 597 =
7. 7.763 − 297 =
8. 8.301 − 197 =
9. 9.501 − 197 =
10. 10.405 − 357 =
11. 11.206 − 188 =
12. 12.776 − 197 =
13. 13.538 − 357 =
14. 14.648 − 407 =
15. 15.718 − 667 =
16. 16.801 − 498 =
17. 17.475 − 199 =
18. 18.844 − 399 =
19. 19.826 − 797 =
20. 20.981 − 417 =
21. 21.832 − 437 =
22. 22.972 − 697 =
23. 23.758 − 257 =
24. 24.742 − 598 =
25. 25.961 − 228 =
26. 26.161 − 117 =
27. 27.543 − 399 =
28. 28.882 − 299 =
29. 29.458 − 298 =
30. 30.979 − 607 =
31. 31.630 − 488 =
32. 32.483 − 397 =
33. 33.872 − 288 =
34. 34.999 − 598 =
35. 35.811 − 697 =
36. 36.505 − 297 =
37. 37.815 − 178 =
38. 38.621 − 377 =
39. 39.786 − 699 =
40. 40.823 − 497 =

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