Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 437 · 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. 1.692 − 119 =
2. 2.775 − 628 =
3. 3.635 − 599 =
4. 4.722 − 499 =
5. 5.723 − 458 =
6. 6.738 − 598 =
7. 7.692 − 197 =
8. 8.885 − 298 =
9. 9.874 − 497 =
10. 10.997 − 429 =
11. 11.937 − 699 =
12. 12.768 − 458 =
13. 13.914 − 128 =
14. 14.446 − 177 =
15. 15.841 − 698 =
16. 16.477 − 297 =
17. 17.336 − 297 =
18. 18.770 − 407 =
19. 19.895 − 198 =
20. 20.985 − 428 =
21. 21.173 − 147 =
22. 22.273 − 137 =
23. 23.395 − 297 =
24. 24.921 − 648 =
25. 25.675 − 397 =
26. 26.734 − 157 =
27. 27.663 − 598 =
28. 28.633 − 598 =
29. 29.945 − 698 =
30. 30.972 − 698 =
31. 31.733 − 678 =
32. 32.924 − 569 =
33. 33.475 − 199 =
34. 34.366 − 187 =
35. 35.659 − 399 =
36. 36.801 − 499 =
37. 37.720 − 699 =
38. 38.884 − 507 =
39. 39.903 − 648 =
40. 40.998 − 638 =

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