3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 915 · 40 questions

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

1. 1.761 − 421 =
2. 2.635 + 291 =
3. 3.755 − 427 =
4. 4.488 − 251 =
5. 5.754 − 543 =
6. 6.655 − 333 =
7. 7.928 − 722 =
8. 8.598 + 556 =
9. 9.721 − 448 =
10. 10.737 + 581 =
11. 11.537 + 205 =
12. 12.576 − 331 =
13. 13.733 + 611 =
14. 14.861 − 401 =
15. 15.389 + 555 =
16. 16.950 − 282 =
17. 17.538 + 284 =
18. 18.779 + 204 =
19. 19.527 + 338 =
20. 20.433 + 347 =
21. 21.693 + 432 =
22. 22.445 − 217 =
23. 23.587 − 227 =
24. 24.636 − 498 =
25. 25.586 + 367 =
26. 26.897 − 652 =
27. 27.368 + 169 =
28. 28.212 + 599 =
29. 29.967 − 431 =
30. 30.480 − 269 =
31. 31.428 − 267 =
32. 32.732 − 296 =
33. 33.620 − 351 =
34. 34.159 + 286 =
35. 35.140 + 522 =
36. 36.443 − 172 =
37. 37.624 + 647 =
38. 38.776 − 568 =
39. 39.714 − 538 =
40. 40.691 − 568 =

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