3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 952 · 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. 1.306 + 287 =
2. 2.411 + 669 =
3. 3.350 + 376 =
4. 4.559 − 133 =
5. 5.432 + 605 =
6. 6.737 − 625 =
7. 7.475 − 268 =
8. 8.628 + 671 =
9. 9.127 + 166 =
10. 10.747 + 633 =
11. 11.541 − 173 =
12. 12.533 + 441 =
13. 13.464 + 664 =
14. 14.297 + 133 =
15. 15.975 − 152 =
16. 16.591 − 325 =
17. 17.189 + 592 =
18. 18.521 − 196 =
19. 19.526 − 121 =
20. 20.977 − 148 =
21. 21.626 − 187 =
22. 22.718 − 144 =
23. 23.515 + 642 =
24. 24.682 − 344 =
25. 25.724 + 393 =
26. 26.312 + 636 =
27. 27.546 + 429 =
28. 28.276 + 196 =
29. 29.252 + 124 =
30. 30.534 + 116 =
31. 31.298 + 518 =
32. 32.244 + 538 =
33. 33.483 + 571 =
34. 34.552 + 303 =
35. 35.513 − 173 =
36. 36.960 − 643 =
37. 37.563 − 199 =
38. 38.521 − 171 =
39. 39.628 + 491 =
40. 40.859 − 575 =

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