Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 589 · 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. 1.698 − 598 =
2. 2.901 − 498 =
3. 3.493 − 308 =
4. 4.397 − 198 =
5. 5.238 − 159 =
6. 6.700 − 499 =
7. 7.548 − 487 =
8. 8.397 − 189 =
9. 9.913 − 498 =
10. 10.726 − 248 =
11. 11.647 − 297 =
12. 12.705 − 399 =
13. 13.844 − 349 =
14. 14.536 − 299 =
15. 15.673 − 599 =
16. 16.650 − 429 =
17. 17.952 − 799 =
18. 18.339 − 247 =
19. 19.637 − 149 =
20. 20.880 − 649 =
21. 21.842 − 498 =
22. 22.691 − 428 =
23. 23.432 − 398 =
24. 24.916 − 397 =
25. 25.720 − 598 =
26. 26.920 − 498 =
27. 27.443 − 398 =
28. 28.945 − 629 =
29. 29.524 − 307 =
30. 30.412 − 238 =
31. 31.538 − 357 =
32. 32.974 − 687 =
33. 33.707 − 219 =
34. 34.915 − 798 =
35. 35.521 − 499 =
36. 36.739 − 298 =
37. 37.828 − 198 =
38. 38.982 − 628 =
39. 39.623 − 399 =
40. 40.972 − 248 =

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