3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 79 · 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. 1.732 + 621 =
2. 2.464 − 112 =
3. 3.768 − 576 =
4. 4.282 + 527 =
5. 5.649 + 317 =
6. 6.810 − 681 =
7. 7.500 − 271 =
8. 8.556 + 595 =
9. 9.877 − 481 =
10. 10.311 + 613 =
11. 11.362 + 112 =
12. 12.710 − 452 =
13. 13.314 + 271 =
14. 14.144 + 652 =
15. 15.489 − 155 =
16. 16.135 + 523 =
17. 17.502 − 238 =
18. 18.733 − 181 =
19. 19.619 − 134 =
20. 20.460 + 344 =
21. 21.676 − 192 =
22. 22.202 + 617 =
23. 23.870 − 541 =
24. 24.583 − 465 =
25. 25.159 + 278 =
26. 26.736 − 501 =
27. 27.742 + 241 =
28. 28.971 − 172 =
29. 29.357 + 601 =
30. 30.443 − 158 =
31. 31.878 − 731 =
32. 32.822 − 622 =
33. 33.564 − 442 =
34. 34.533 + 329 =
35. 35.160 + 486 =
36. 36.542 + 381 =
37. 37.781 − 489 =
38. 38.630 + 482 =
39. 39.899 − 778 =
40. 40.317 + 354 =

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