3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 775 · 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. 1.601 − 201 =
2. 2.715 + 454 =
3. 3.457 + 138 =
4. 4.208 + 529 =
5. 5.191 + 575 =
6. 6.615 − 179 =
7. 7.796 − 472 =
8. 8.389 + 268 =
9. 9.527 − 136 =
10. 10.124 + 637 =
11. 11.675 − 468 =
12. 12.930 − 736 =
13. 13.774 − 484 =
14. 14.911 − 592 =
15. 15.855 − 381 =
16. 16.332 + 438 =
17. 17.814 − 251 =
18. 18.532 − 387 =
19. 19.276 + 501 =
20. 20.844 − 443 =
21. 21.193 + 324 =
22. 22.774 + 245 =
23. 23.721 − 168 =
24. 24.477 + 615 =
25. 25.426 + 245 =
26. 26.408 + 247 =
27. 27.258 + 152 =
28. 28.681 − 458 =
29. 29.933 − 172 =
30. 30.815 − 245 =
31. 31.417 + 178 =
32. 32.845 − 466 =
33. 33.126 + 479 =
34. 34.665 + 376 =
35. 35.133 + 251 =
36. 36.433 − 161 =
37. 37.894 − 278 =
38. 38.909 − 356 =
39. 39.416 − 128 =
40. 40.969 − 553 =

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