Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 15 · 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. 1.851 − 798 =
2. 2.660 − 359 =
3. 3.198 − 177 =
4. 4.594 − 198 =
5. 5.965 − 637 =
6. 6.218 − 167 =
7. 7.658 − 639 =
8. 8.650 − 179 =
9. 9.724 − 499 =
10. 10.845 − 398 =
11. 11.745 − 367 =
12. 12.337 − 188 =
13. 13.830 − 197 =
14. 14.430 − 238 =
15. 15.817 − 119 =
16. 16.356 − 297 =
17. 17.881 − 539 =
18. 18.815 − 697 =
19. 19.775 − 497 =
20. 20.549 − 399 =
21. 21.629 − 139 =
22. 22.558 − 197 =
23. 23.447 − 397 =
24. 24.964 − 297 =
25. 25.604 − 197 =
26. 26.909 − 799 =
27. 27.860 − 298 =
28. 28.583 − 308 =
29. 29.240 − 217 =
30. 30.847 − 797 =
31. 31.826 − 508 =
32. 32.771 − 597 =
33. 33.942 − 499 =
34. 34.761 − 178 =
35. 35.345 − 197 =
36. 36.811 − 299 =
37. 37.147 − 129 =
38. 38.858 − 797 =
39. 39.903 − 398 =
40. 40.259 − 197 =

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