Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 417 · 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. 1.697 − 398 =
2. 2.983 − 599 =
3. 3.698 − 598 =
4. 4.828 − 798 =
5. 5.212 − 137 =
6. 6.479 − 297 =
7. 7.599 − 399 =
8. 8.936 − 797 =
9. 9.686 − 487 =
10. 10.921 − 399 =
11. 11.813 − 299 =
12. 12.624 − 497 =
13. 13.333 − 197 =
14. 14.874 − 397 =
15. 15.439 − 227 =
16. 16.984 − 697 =
17. 17.888 − 497 =
18. 18.693 − 649 =
19. 19.848 − 198 =
20. 20.634 − 479 =
21. 21.927 − 397 =
22. 22.316 − 227 =
23. 23.758 − 598 =
24. 24.574 − 419 =
25. 25.310 − 199 =
26. 26.702 − 567 =
27. 27.568 − 449 =
28. 28.936 − 398 =
29. 29.867 − 797 =
30. 30.912 − 279 =
31. 31.585 − 428 =
32. 32.977 − 697 =
33. 33.864 − 797 =
34. 34.731 − 197 =
35. 35.279 − 119 =
36. 36.793 − 397 =
37. 37.650 − 599 =
38. 38.454 − 259 =
39. 39.516 − 117 =
40. 40.870 − 418 =

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