Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 342 · 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. 1.584 − 387 =
2. 2.535 − 169 =
3. 3.815 − 797 =
4. 4.760 − 588 =
5. 5.712 − 499 =
6. 6.464 − 299 =
7. 7.293 − 257 =
8. 8.702 − 298 =
9. 9.923 − 797 =
10. 10.942 − 608 =
11. 11.910 − 797 =
12. 12.883 − 347 =
13. 13.747 − 699 =
14. 14.943 − 208 =
15. 15.360 − 298 =
16. 16.998 − 199 =
17. 17.480 − 327 =
18. 18.608 − 498 =
19. 19.395 − 297 =
20. 20.895 − 328 =
21. 21.607 − 347 =
22. 22.903 − 208 =
23. 23.746 − 168 =
24. 24.739 − 499 =
25. 25.758 − 397 =
26. 26.357 − 299 =
27. 27.611 − 499 =
28. 28.939 − 638 =
29. 29.564 − 398 =
30. 30.600 − 297 =
31. 31.979 − 798 =
32. 32.713 − 398 =
33. 33.671 − 589 =
34. 34.854 − 198 =
35. 35.620 − 238 =
36. 36.434 − 199 =
37. 37.599 − 578 =
38. 38.363 − 148 =
39. 39.422 − 299 =
40. 40.534 − 399 =

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