Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 644 · 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. 1.902 − 799 =
2. 2.804 − 688 =
3. 3.301 − 187 =
4. 4.574 − 248 =
5. 5.736 − 248 =
6. 6.389 − 299 =
7. 7.879 − 797 =
8. 8.754 − 247 =
9. 9.638 − 177 =
10. 10.967 − 499 =
11. 11.478 − 197 =
12. 12.763 − 397 =
13. 13.516 − 378 =
14. 14.643 − 438 =
15. 15.726 − 628 =
16. 16.742 − 228 =
17. 17.557 − 398 =
18. 18.679 − 439 =
19. 19.804 − 199 =
20. 20.861 − 399 =
21. 21.985 − 568 =
22. 22.710 − 417 =
23. 23.759 − 499 =
24. 24.724 − 539 =
25. 25.737 − 698 =
26. 26.492 − 297 =
27. 27.834 − 799 =
28. 28.600 − 398 =
29. 29.650 − 298 =
30. 30.606 − 339 =
31. 31.982 − 457 =
32. 32.467 − 248 =
33. 33.705 − 659 =
34. 34.951 − 439 =
35. 35.932 − 597 =
36. 36.339 − 199 =
37. 37.712 − 567 =
38. 38.849 − 347 =
39. 39.914 − 397 =
40. 40.709 − 638 =

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