Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 122 · 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. 1.557 − 298 =
2. 2.552 − 389 =
3. 3.534 − 299 =
4. 4.987 − 489 =
5. 5.811 − 399 =
6. 6.579 − 399 =
7. 7.471 − 439 =
8. 8.970 − 507 =
9. 9.629 − 509 =
10. 10.577 − 339 =
11. 11.825 − 797 =
12. 12.862 − 297 =
13. 13.463 − 419 =
14. 14.835 − 358 =
15. 15.415 − 397 =
16. 16.937 − 799 =
17. 17.242 − 208 =
18. 18.904 − 637 =
19. 19.759 − 499 =
20. 20.494 − 369 =
21. 21.568 − 499 =
22. 22.823 − 798 =
23. 23.794 − 449 =
24. 24.737 − 399 =
25. 25.770 − 697 =
26. 26.724 − 507 =
27. 27.755 − 498 =
28. 28.846 − 299 =
29. 29.940 − 799 =
30. 30.828 − 387 =
31. 31.540 − 399 =
32. 32.537 − 388 =
33. 33.706 − 629 =
34. 34.937 − 199 =
35. 35.727 − 599 =
36. 36.649 − 117 =
37. 37.932 − 509 =
38. 38.561 − 297 =
39. 39.894 − 488 =
40. 40.776 − 178 =

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