3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 458 · 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. 1.433 − 239 =
2. 2.326 + 357 =
3. 3.453 − 207 =
4. 4.884 − 134 =
5. 5.566 − 287 =
6. 6.686 − 316 =
7. 7.581 − 271 =
8. 8.324 + 404 =
9. 9.670 + 556 =
10. 10.483 − 156 =
11. 11.507 − 161 =
12. 12.272 + 524 =
13. 13.474 + 671 =
14. 14.629 − 449 =
15. 15.205 + 145 =
16. 16.514 + 275 =
17. 17.649 − 478 =
18. 18.156 + 374 =
19. 19.573 − 191 =
20. 20.640 + 675 =
21. 21.467 + 114 =
22. 22.820 − 539 =
23. 23.639 + 519 =
24. 24.443 + 544 =
25. 25.141 + 303 =
26. 26.343 + 609 =
27. 27.484 − 377 =
28. 28.705 − 308 =
29. 29.367 + 389 =
30. 30.520 − 319 =
31. 31.769 + 448 =
32. 32.364 + 152 =
33. 33.519 + 444 =
34. 34.510 + 151 =
35. 35.293 + 346 =
36. 36.423 + 674 =
37. 37.780 + 533 =
38. 38.943 − 321 =
39. 39.967 − 295 =
40. 40.866 − 341 =

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