Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 387 · 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. 1.999 − 309 =
2. 2.574 − 277 =
3. 3.838 − 599 =
4. 4.990 − 199 =
5. 5.921 − 597 =
6. 6.943 − 798 =
7. 7.927 − 259 =
8. 8.490 − 389 =
9. 9.685 − 297 =
10. 10.467 − 359 =
11. 11.813 − 798 =
12. 12.926 − 599 =
13. 13.916 − 397 =
14. 14.960 − 198 =
15. 15.652 − 619 =
16. 16.700 − 588 =
17. 17.292 − 208 =
18. 18.748 − 299 =
19. 19.428 − 298 =
20. 20.665 − 159 =
21. 21.985 − 498 =
22. 22.455 − 399 =
23. 23.667 − 499 =
24. 24.945 − 437 =
25. 25.905 − 578 =
26. 26.569 − 438 =
27. 27.891 − 698 =
28. 28.645 − 599 =
29. 29.876 − 798 =
30. 30.397 − 288 =
31. 31.330 − 199 =
32. 32.535 − 219 =
33. 33.984 − 799 =
34. 34.923 − 699 =
35. 35.888 − 699 =
36. 36.731 − 299 =
37. 37.598 − 529 =
38. 38.923 − 598 =
39. 39.741 − 588 =
40. 40.583 − 239 =

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