Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 255 · 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. 1.899 − 507 =
2. 2.869 − 458 =
3. 3.461 − 299 =
4. 4.648 − 609 =
5. 5.720 − 168 =
6. 6.445 − 398 =
7. 7.833 − 297 =
8. 8.631 − 197 =
9. 9.666 − 558 =
10. 10.473 − 437 =
11. 11.853 − 799 =
12. 12.556 − 499 =
13. 13.849 − 399 =
14. 14.774 − 479 =
15. 15.320 − 197 =
16. 16.842 − 269 =
17. 17.975 − 797 =
18. 18.860 − 198 =
19. 19.791 − 658 =
20. 20.819 − 798 =
21. 21.962 − 557 =
22. 22.403 − 247 =
23. 23.855 − 199 =
24. 24.800 − 547 =
25. 25.803 − 397 =
26. 26.938 − 599 =
27. 27.736 − 399 =
28. 28.631 − 198 =
29. 29.780 − 569 =
30. 30.427 − 299 =
31. 31.612 − 598 =
32. 32.785 − 397 =
33. 33.477 − 299 =
34. 34.340 − 298 =
35. 35.598 − 177 =
36. 36.781 − 298 =
37. 37.882 − 668 =
38. 38.679 − 499 =
39. 39.635 − 457 =
40. 40.760 − 598 =

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