Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 631 · 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. 1.340 − 188 =
2. 2.933 − 598 =
3. 3.565 − 498 =
4. 4.433 − 187 =
5. 5.785 − 499 =
6. 6.962 − 698 =
7. 7.209 − 168 =
8. 8.725 − 277 =
9. 9.879 − 497 =
10. 10.629 − 598 =
11. 11.924 − 298 =
12. 12.658 − 119 =
13. 13.910 − 299 =
14. 14.619 − 218 =
15. 15.526 − 398 =
16. 16.368 − 298 =
17. 17.830 − 799 =
18. 18.281 − 198 =
19. 19.720 − 578 =
20. 20.632 − 299 =
21. 21.822 − 498 =
22. 22.600 − 298 =
23. 23.782 − 359 =
24. 24.494 − 448 =
25. 25.580 − 369 =
26. 26.914 − 508 =
27. 27.907 − 199 =
28. 28.804 − 297 =
29. 29.591 − 498 =
30. 30.802 − 538 =
31. 31.421 − 177 =
32. 32.618 − 539 =
33. 33.982 − 649 =
34. 34.755 − 568 =
35. 35.833 − 799 =
36. 36.317 − 297 =
37. 37.900 − 169 =
38. 38.613 − 197 =
39. 39.672 − 599 =
40. 40.886 − 479 =

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