3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 811 · 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. 1.461 + 357 =
2. 2.455 − 345 =
3. 3.768 − 371 =
4. 4.413 + 198 =
5. 5.866 − 291 =
6. 6.574 + 194 =
7. 7.336 + 641 =
8. 8.765 + 167 =
9. 9.164 + 228 =
10. 10.229 + 361 =
11. 11.146 + 121 =
12. 12.366 + 124 =
13. 13.533 + 476 =
14. 14.774 − 287 =
15. 15.584 − 393 =
16. 16.128 + 349 =
17. 17.590 − 181 =
18. 18.297 + 629 =
19. 19.182 + 306 =
20. 20.632 − 118 =
21. 21.168 + 183 =
22. 22.657 − 433 =
23. 23.943 − 612 =
24. 24.892 − 699 =
25. 25.326 + 369 =
26. 26.284 + 201 =
27. 27.285 + 584 =
28. 28.781 + 657 =
29. 29.806 − 501 =
30. 30.659 + 163 =
31. 31.401 + 579 =
32. 32.494 − 123 =
33. 33.163 + 565 =
34. 34.607 − 251 =
35. 35.977 − 523 =
36. 36.524 + 659 =
37. 37.674 + 136 =
38. 38.167 + 581 =
39. 39.765 − 144 =
40. 40.565 + 654 =

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