3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 492 · 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. 1.808 − 406 =
2. 2.934 − 187 =
3. 3.520 − 201 =
4. 4.573 − 399 =
5. 5.194 + 124 =
6. 6.725 + 137 =
7. 7.244 + 676 =
8. 8.447 + 128 =
9. 9.526 + 381 =
10. 10.853 − 654 =
11. 11.438 + 365 =
12. 12.735 + 425 =
13. 13.971 − 659 =
14. 14.720 + 455 =
15. 15.689 + 445 =
16. 16.958 − 839 =
17. 17.614 − 508 =
18. 18.308 + 491 =
19. 19.474 − 325 =
20. 20.746 + 117 =
21. 21.917 − 529 =
22. 22.572 + 381 =
23. 23.338 + 287 =
24. 24.643 − 455 =
25. 25.562 + 321 =
26. 26.661 − 201 =
27. 27.584 + 249 =
28. 28.676 + 541 =
29. 29.884 − 541 =
30. 30.240 + 389 =
31. 31.584 + 377 =
32. 32.687 − 188 =
33. 33.702 − 166 =
34. 34.503 + 558 =
35. 35.175 + 199 =
36. 36.610 − 201 =
37. 37.459 + 506 =
38. 38.588 + 154 =
39. 39.976 − 668 =
40. 40.442 + 645 =

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