Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 659 · 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. 1.917 − 699 =
2. 2.389 − 289 =
3. 3.973 − 499 =
4. 4.587 − 298 =
5. 5.990 − 227 =
6. 6.968 − 797 =
7. 7.862 − 697 =
8. 8.740 − 647 =
9. 9.728 − 589 =
10. 10.600 − 499 =
11. 11.782 − 259 =
12. 12.792 − 638 =
13. 13.824 − 498 =
14. 14.559 − 468 =
15. 15.877 − 619 =
16. 16.840 − 197 =
17. 17.454 − 398 =
18. 18.630 − 299 =
19. 19.582 − 308 =
20. 20.535 − 448 =
21. 21.806 − 298 =
22. 22.894 − 199 =
23. 23.960 − 598 =
24. 24.858 − 797 =
25. 25.469 − 217 =
26. 26.811 − 429 =
27. 27.679 − 239 =
28. 28.973 − 597 =
29. 29.868 − 297 =
30. 30.773 − 237 =
31. 31.647 − 597 =
32. 32.864 − 598 =
33. 33.468 − 377 =
34. 34.685 − 298 =
35. 35.677 − 217 =
36. 36.807 − 399 =
37. 37.716 − 617 =
38. 38.990 − 397 =
39. 39.808 − 398 =
40. 40.466 − 199 =

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