Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 107 · 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. 1.807 − 299 =
2. 2.880 − 199 =
3. 3.797 − 298 =
4. 4.491 − 197 =
5. 5.408 − 197 =
6. 6.783 − 359 =
7. 7.451 − 339 =
8. 8.426 − 237 =
9. 9.882 − 798 =
10. 10.929 − 427 =
11. 11.657 − 168 =
12. 12.355 − 318 =
13. 13.877 − 799 =
14. 14.893 − 499 =
15. 15.838 − 599 =
16. 16.991 − 397 =
17. 17.974 − 398 =
18. 18.959 − 297 =
19. 19.923 − 407 =
20. 20.867 − 378 =
21. 21.901 − 378 =
22. 22.736 − 639 =
23. 23.184 − 169 =
24. 24.508 − 189 =
25. 25.712 − 457 =
26. 26.904 − 327 =
27. 27.607 − 397 =
28. 28.695 − 349 =
29. 29.901 − 689 =
30. 30.546 − 138 =
31. 31.835 − 569 =
32. 32.830 − 499 =
33. 33.848 − 798 =
34. 34.955 − 698 =
35. 35.741 − 699 =
36. 36.998 − 598 =
37. 37.971 − 538 =
38. 38.613 − 398 =
39. 39.248 − 199 =
40. 40.915 − 269 =

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