Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 203 · 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. 1.874 − 798 =
2. 2.693 − 297 =
3. 3.926 − 699 =
4. 4.670 − 597 =
5. 5.267 − 147 =
6. 6.722 − 658 =
7. 7.845 − 297 =
8. 8.819 − 299 =
9. 9.672 − 218 =
10. 10.833 − 497 =
11. 11.360 − 297 =
12. 12.206 − 188 =
13. 13.714 − 698 =
14. 14.924 − 799 =
15. 15.429 − 297 =
16. 16.877 − 798 =
17. 17.428 − 329 =
18. 18.491 − 399 =
19. 19.834 − 197 =
20. 20.796 − 118 =
21. 21.419 − 178 =
22. 22.618 − 599 =
23. 23.802 − 499 =
24. 24.773 − 359 =
25. 25.612 − 397 =
26. 26.671 − 499 =
27. 27.484 − 199 =
28. 28.727 − 588 =
29. 29.460 − 428 =
30. 30.499 − 298 =
31. 31.974 − 299 =
32. 32.632 − 177 =
33. 33.627 − 518 =
34. 34.887 − 297 =
35. 35.489 − 337 =
36. 36.727 − 399 =
37. 37.573 − 498 =
38. 38.566 − 369 =
39. 39.801 − 399 =
40. 40.883 − 658 =

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