Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 330 · 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. 1.814 − 199 =
2. 2.384 − 337 =
3. 3.840 − 258 =
4. 4.483 − 269 =
5. 5.876 − 799 =
6. 6.533 − 299 =
7. 7.319 − 157 =
8. 8.417 − 208 =
9. 9.490 − 329 =
10. 10.675 − 379 =
11. 11.718 − 317 =
12. 12.626 − 397 =
13. 13.968 − 697 =
14. 14.817 − 298 =
15. 15.849 − 297 =
16. 16.606 − 398 =
17. 17.584 − 337 =
18. 18.572 − 248 =
19. 19.772 − 399 =
20. 20.744 − 588 =
21. 21.895 − 139 =
22. 22.880 − 198 =
23. 23.513 − 197 =
24. 24.499 − 298 =
25. 25.871 − 398 =
26. 26.616 − 517 =
27. 27.968 − 598 =
28. 28.473 − 328 =
29. 29.751 − 147 =
30. 30.557 − 467 =
31. 31.805 − 358 =
32. 32.298 − 229 =
33. 33.566 − 498 =
34. 34.425 − 299 =
35. 35.973 − 397 =
36. 36.891 − 607 =
37. 37.681 − 598 =
38. 38.957 − 499 =
39. 39.470 − 358 =
40. 40.912 − 198 =

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