Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 843 · 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. 1.628 − 149 =
2. 2.900 − 798 =
3. 3.231 − 197 =
4. 4.603 − 569 =
5. 5.224 − 198 =
6. 6.836 − 297 =
7. 7.832 − 197 =
8. 8.541 − 399 =
9. 9.535 − 198 =
10. 10.831 − 509 =
11. 11.787 − 599 =
12. 12.695 − 498 =
13. 13.987 − 697 =
14. 14.209 − 189 =
15. 15.540 − 299 =
16. 16.424 − 198 =
17. 17.537 − 499 =
18. 18.753 − 197 =
19. 19.546 − 227 =
20. 20.330 − 249 =
21. 21.555 − 497 =
22. 22.725 − 407 =
23. 23.484 − 178 =
24. 24.285 − 197 =
25. 25.860 − 347 =
26. 26.824 − 598 =
27. 27.264 − 199 =
28. 28.725 − 278 =
29. 29.367 − 298 =
30. 30.892 − 199 =
31. 31.715 − 197 =
32. 32.294 − 138 =
33. 33.873 − 508 =
34. 34.668 − 539 =
35. 35.954 − 497 =
36. 36.544 − 399 =
37. 37.421 − 399 =
38. 38.244 − 177 =
39. 39.527 − 357 =
40. 40.982 − 689 =

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