Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 300 · 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. 1.435 − 179 =
2. 2.465 − 318 =
3. 3.859 − 498 =
4. 4.700 − 497 =
5. 5.782 − 197 =
6. 6.334 − 199 =
7. 7.935 − 797 =
8. 8.666 − 349 =
9. 9.486 − 197 =
10. 10.809 − 397 =
11. 11.881 − 799 =
12. 12.905 − 598 =
13. 13.943 − 499 =
14. 14.821 − 797 =
15. 15.438 − 399 =
16. 16.944 − 797 =
17. 17.700 − 199 =
18. 18.719 − 618 =
19. 19.562 − 158 =
20. 20.634 − 239 =
21. 21.365 − 127 =
22. 22.491 − 398 =
23. 23.936 − 697 =
24. 24.767 − 697 =
25. 25.310 − 199 =
26. 26.808 − 689 =
27. 27.994 − 798 =
28. 28.571 − 199 =
29. 29.814 − 797 =
30. 30.982 − 299 =
31. 31.585 − 429 =
32. 32.960 − 697 =
33. 33.597 − 139 =
34. 34.990 − 248 =
35. 35.799 − 499 =
36. 36.396 − 299 =
37. 37.964 − 799 =
38. 38.385 − 189 =
39. 39.501 − 459 =
40. 40.835 − 438 =

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