3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 301 · 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. 1.909 − 788 =
2. 2.751 + 448 =
3. 3.461 − 137 =
4. 4.739 − 235 =
5. 5.841 − 161 =
6. 6.240 + 372 =
7. 7.388 + 367 =
8. 8.471 − 339 =
9. 9.738 + 656 =
10. 10.410 + 232 =
11. 11.481 − 112 =
12. 12.609 − 299 =
13. 13.571 − 177 =
14. 14.222 + 328 =
15. 15.136 + 484 =
16. 16.901 − 603 =
17. 17.388 + 516 =
18. 18.252 + 435 =
19. 19.239 + 459 =
20. 20.879 − 409 =
21. 21.456 − 179 =
22. 22.556 + 654 =
23. 23.674 − 168 =
24. 24.803 − 177 =
25. 25.765 + 599 =
26. 26.751 − 562 =
27. 27.717 + 318 =
28. 28.759 − 155 =
29. 29.579 − 175 =
30. 30.353 + 538 =
31. 31.314 + 514 =
32. 32.715 − 468 =
33. 33.498 − 378 =
34. 34.682 − 462 =
35. 35.563 − 394 =
36. 36.563 − 191 =
37. 37.136 + 269 =
38. 38.714 + 197 =
39. 39.770 − 142 =
40. 40.203 + 441 =

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