Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 808 · 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. 1.679 − 127 =
2. 2.749 − 347 =
3. 3.588 − 257 =
4. 4.738 − 297 =
5. 5.706 − 197 =
6. 6.851 − 238 =
7. 7.287 − 149 =
8. 8.891 − 368 =
9. 9.932 − 397 =
10. 10.713 − 218 =
11. 11.933 − 217 =
12. 12.633 − 229 =
13. 13.470 − 399 =
14. 14.703 − 599 =
15. 15.664 − 598 =
16. 16.966 − 318 =
17. 17.609 − 238 =
18. 18.567 − 327 =
19. 19.777 − 359 =
20. 20.526 − 429 =
21. 21.736 − 188 =
22. 22.564 − 437 =
23. 23.970 − 797 =
24. 24.842 − 198 =
25. 25.489 − 299 =
26. 26.830 − 699 =
27. 27.948 − 598 =
28. 28.766 − 639 =
29. 29.406 − 159 =
30. 30.690 − 587 =
31. 31.541 − 277 =
32. 32.866 − 198 =
33. 33.442 − 297 =
34. 34.886 − 197 =
35. 35.346 − 199 =
36. 36.616 − 128 =
37. 37.775 − 297 =
38. 38.515 − 137 =
39. 39.738 − 698 =
40. 40.238 − 168 =

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