Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 46 · 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. 1.999 − 598 =
2. 2.915 − 297 =
3. 3.899 − 518 =
4. 4.641 − 298 =
5. 5.177 − 148 =
6. 6.732 − 458 =
7. 7.668 − 297 =
8. 8.329 − 299 =
9. 9.612 − 479 =
10. 10.965 − 799 =
11. 11.378 − 259 =
12. 12.513 − 399 =
13. 13.768 − 689 =
14. 14.258 − 228 =
15. 15.626 − 298 =
16. 16.261 − 198 =
17. 17.816 − 597 =
18. 18.763 − 368 =
19. 19.547 − 498 =
20. 20.744 − 499 =
21. 21.883 − 498 =
22. 22.898 − 698 =
23. 23.787 − 487 =
24. 24.849 − 599 =
25. 25.978 − 799 =
26. 26.686 − 499 =
27. 27.777 − 408 =
28. 28.317 − 299 =
29. 29.718 − 697 =
30. 30.689 − 439 =
31. 31.545 − 229 =
32. 32.414 − 397 =
33. 33.650 − 297 =
34. 34.412 − 197 =
35. 35.646 − 597 =
36. 36.613 − 258 =
37. 37.908 − 799 =
38. 38.928 − 659 =
39. 39.748 − 369 =
40. 40.614 − 457 =

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