Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 148 · 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. 1.337 − 159 =
2. 2.988 − 798 =
3. 3.618 − 269 =
4. 4.921 − 798 =
5. 5.974 − 617 =
6. 6.913 − 797 =
7. 7.976 − 798 =
8. 8.937 − 299 =
9. 9.395 − 198 =
10. 10.681 − 118 =
11. 11.561 − 397 =
12. 12.628 − 169 =
13. 13.867 − 217 =
14. 14.985 − 197 =
15. 15.630 − 197 =
16. 16.239 − 187 =
17. 17.969 − 497 =
18. 18.828 − 799 =
19. 19.486 − 389 =
20. 20.519 − 397 =
21. 21.489 − 268 =
22. 22.639 − 298 =
23. 23.568 − 399 =
24. 24.527 − 199 =
25. 25.376 − 158 =
26. 26.879 − 698 =
27. 27.462 − 169 =
28. 28.954 − 117 =
29. 29.806 − 699 =
30. 30.982 − 497 =
31. 31.286 − 169 =
32. 32.836 − 698 =
33. 33.437 − 369 =
34. 34.946 − 597 =
35. 35.372 − 279 =
36. 36.900 − 237 =
37. 37.343 − 307 =
38. 38.720 − 269 =
39. 39.463 − 399 =
40. 40.583 − 399 =

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