Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 299 · 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. 1.486 − 297 =
2. 2.988 − 499 =
3. 3.556 − 288 =
4. 4.799 − 187 =
5. 5.300 − 188 =
6. 6.824 − 178 =
7. 7.746 − 497 =
8. 8.912 − 557 =
9. 9.786 − 579 =
10. 10.654 − 247 =
11. 11.583 − 399 =
12. 12.659 − 297 =
13. 13.597 − 318 =
14. 14.816 − 797 =
15. 15.771 − 298 =
16. 16.781 − 459 =
17. 17.947 − 797 =
18. 18.731 − 499 =
19. 19.936 − 459 =
20. 20.846 − 699 =
21. 21.801 − 619 =
22. 22.547 − 208 =
23. 23.543 − 399 =
24. 24.915 − 797 =
25. 25.724 − 597 =
26. 26.747 − 639 =
27. 27.527 − 497 =
28. 28.974 − 519 =
29. 29.923 − 597 =
30. 30.469 − 187 =
31. 31.982 − 598 =
32. 32.630 − 248 =
33. 33.942 − 559 =
34. 34.553 − 399 =
35. 35.975 − 409 =
36. 36.471 − 409 =
37. 37.494 − 148 =
38. 38.644 − 457 =
39. 39.480 − 199 =
40. 40.642 − 497 =

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