Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 688 · 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. 1.299 − 188 =
2. 2.435 − 399 =
3. 3.598 − 399 =
4. 4.768 − 597 =
5. 5.801 − 699 =
6. 6.657 − 398 =
7. 7.683 − 288 =
8. 8.758 − 319 =
9. 9.589 − 298 =
10. 10.725 − 329 =
11. 11.785 − 148 =
12. 12.894 − 459 =
13. 13.808 − 408 =
14. 14.307 − 199 =
15. 15.683 − 307 =
16. 16.974 − 438 =
17. 17.544 − 199 =
18. 18.722 − 657 =
19. 19.514 − 299 =
20. 20.911 − 299 =
21. 21.842 − 799 =
22. 22.457 − 379 =
23. 23.507 − 427 =
24. 24.925 − 249 =
25. 25.838 − 129 =
26. 26.804 − 697 =
27. 27.999 − 799 =
28. 28.674 − 579 =
29. 29.971 − 149 =
30. 30.514 − 127 =
31. 31.807 − 307 =
32. 32.369 − 299 =
33. 33.932 − 197 =
34. 34.896 − 399 =
35. 35.977 − 599 =
36. 36.993 − 497 =
37. 37.755 − 699 =
38. 38.961 − 598 =
39. 39.717 − 247 =
40. 40.864 − 497 =

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