Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 552 · 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. 1.642 − 199 =
2. 2.591 − 249 =
3. 3.806 − 397 =
4. 4.622 − 499 =
5. 5.558 − 399 =
6. 6.433 − 398 =
7. 7.600 − 397 =
8. 8.952 − 498 =
9. 9.955 − 479 =
10. 10.651 − 497 =
11. 11.886 − 697 =
12. 12.743 − 699 =
13. 13.483 − 399 =
14. 14.915 − 648 =
15. 15.536 − 438 =
16. 16.857 − 649 =
17. 17.803 − 598 =
18. 18.380 − 298 =
19. 19.945 − 689 =
20. 20.726 − 199 =
21. 21.445 − 297 =
22. 22.606 − 218 =
23. 23.845 − 698 =
24. 24.997 − 799 =
25. 25.668 − 497 =
26. 26.889 − 699 =
27. 27.303 − 148 =
28. 28.917 − 507 =
29. 29.455 − 198 =
30. 30.878 − 199 =
31. 31.439 − 397 =
32. 32.835 − 697 =
33. 33.690 − 597 =
34. 34.836 − 799 =
35. 35.878 − 298 =
36. 36.928 − 329 =
37. 37.229 − 208 =
38. 38.616 − 119 =
39. 39.294 − 197 =
40. 40.814 − 297 =

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