Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 39 · 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. 1.673 − 398 =
2. 2.734 − 497 =
3. 3.768 − 349 =
4. 4.722 − 699 =
5. 5.891 − 797 =
6. 6.803 − 299 =
7. 7.985 − 498 =
8. 8.985 − 387 =
9. 9.862 − 798 =
10. 10.671 − 578 =
11. 11.778 − 499 =
12. 12.289 − 269 =
13. 13.784 − 589 =
14. 14.225 − 197 =
15. 15.961 − 499 =
16. 16.924 − 799 =
17. 17.376 − 158 =
18. 18.972 − 799 =
19. 19.648 − 598 =
20. 20.383 − 298 =
21. 21.815 − 598 =
22. 22.610 − 398 =
23. 23.751 − 689 =
24. 24.481 − 378 =
25. 25.897 − 549 =
26. 26.913 − 597 =
27. 27.674 − 498 =
28. 28.575 − 267 =
29. 29.917 − 799 =
30. 30.702 − 397 =
31. 31.881 − 799 =
32. 32.693 − 669 =
33. 33.940 − 797 =
34. 34.394 − 289 =
35. 35.699 − 598 =
36. 36.407 − 347 =
37. 37.739 − 299 =
38. 38.643 − 599 =
39. 39.751 − 299 =
40. 40.729 − 607 =

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