3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 505 · 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. 1.374 + 144 =
2. 2.288 + 357 =
3. 3.703 − 319 =
4. 4.672 − 269 =
5. 5.503 − 351 =
6. 6.148 + 321 =
7. 7.650 + 533 =
8. 8.573 − 268 =
9. 9.512 − 233 =
10. 10.380 + 582 =
11. 11.952 − 691 =
12. 12.867 − 522 =
13. 13.655 − 303 =
14. 14.554 − 223 =
15. 15.465 − 175 =
16. 16.785 + 362 =
17. 17.275 + 649 =
18. 18.479 − 134 =
19. 19.911 − 335 =
20. 20.757 + 216 =
21. 21.561 + 235 =
22. 22.975 − 698 =
23. 23.625 + 577 =
24. 24.127 + 564 =
25. 25.509 − 183 =
26. 26.693 + 552 =
27. 27.530 − 362 =
28. 28.697 + 504 =
29. 29.547 − 404 =
30. 30.934 − 331 =
31. 31.696 + 405 =
32. 32.759 + 191 =
33. 33.707 − 222 =
34. 34.208 + 135 =
35. 35.293 + 119 =
36. 36.486 − 318 =
37. 37.598 + 646 =
38. 38.222 + 631 =
39. 39.938 − 543 =
40. 40.496 − 161 =

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