Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 697 · 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. 1.489 − 378 =
2. 2.323 − 299 =
3. 3.733 − 199 =
4. 4.786 − 698 =
5. 5.968 − 199 =
6. 6.872 − 498 =
7. 7.222 − 199 =
8. 8.412 − 199 =
9. 9.866 − 537 =
10. 10.804 − 597 =
11. 11.509 − 229 =
12. 12.481 − 397 =
13. 13.917 − 499 =
14. 14.935 − 398 =
15. 15.537 − 197 =
16. 16.615 − 597 =
17. 17.663 − 199 =
18. 18.981 − 667 =
19. 19.718 − 617 =
20. 20.361 − 197 =
21. 21.561 − 339 =
22. 22.397 − 217 =
23. 23.772 − 498 =
24. 24.428 − 117 =
25. 25.773 − 578 =
26. 26.786 − 197 =
27. 27.309 − 148 =
28. 28.928 − 387 =
29. 29.926 − 599 =
30. 30.916 − 548 =
31. 31.950 − 299 =
32. 32.560 − 398 =
33. 33.449 − 309 =
34. 34.711 − 149 =
35. 35.905 − 219 =
36. 36.894 − 799 =
37. 37.780 − 599 =
38. 38.277 − 187 =
39. 39.424 − 298 =
40. 40.848 − 598 =

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