Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 81 · 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. 1.812 − 398 =
2. 2.479 − 197 =
3. 3.832 − 797 =
4. 4.873 − 209 =
5. 5.757 − 399 =
6. 6.270 − 167 =
7. 7.663 − 498 =
8. 8.979 − 288 =
9. 9.832 − 798 =
10. 10.913 − 799 =
11. 11.885 − 698 =
12. 12.446 − 148 =
13. 13.596 − 518 =
14. 14.914 − 199 =
15. 15.865 − 697 =
16. 16.668 − 199 =
17. 17.323 − 297 =
18. 18.973 − 329 =
19. 19.853 − 299 =
20. 20.939 − 698 =
21. 21.967 − 698 =
22. 22.457 − 197 =
23. 23.882 − 198 =
24. 24.595 − 499 =
25. 25.960 − 699 =
26. 26.567 − 198 =
27. 27.859 − 599 =
28. 28.997 − 497 =
29. 29.456 − 399 =
30. 30.462 − 397 =
31. 31.461 − 299 =
32. 32.193 − 128 =
33. 33.980 − 799 =
34. 34.861 − 538 =
35. 35.999 − 398 =
36. 36.559 − 198 =
37. 37.648 − 227 =
38. 38.552 − 298 =
39. 39.864 − 598 =
40. 40.615 − 598 =

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