3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 379 · 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. 1.338 + 378 =
2. 2.647 − 201 =
3. 3.708 + 345 =
4. 4.147 + 266 =
5. 5.759 − 172 =
6. 6.712 − 214 =
7. 7.516 + 328 =
8. 8.671 − 561 =
9. 9.896 − 117 =
10. 10.793 − 261 =
11. 11.532 + 262 =
12. 12.571 − 224 =
13. 13.223 + 283 =
14. 14.747 − 131 =
15. 15.601 − 369 =
16. 16.142 + 269 =
17. 17.735 + 235 =
18. 18.659 − 271 =
19. 19.415 − 175 =
20. 20.462 − 164 =
21. 21.808 − 211 =
22. 22.675 − 323 =
23. 23.469 − 329 =
24. 24.753 − 447 =
25. 25.219 + 261 =
26. 26.985 − 799 =
27. 27.423 − 311 =
28. 28.561 − 176 =
29. 29.980 − 482 =
30. 30.180 + 439 =
31. 31.633 + 155 =
32. 32.853 − 379 =
33. 33.405 + 386 =
34. 34.226 + 623 =
35. 35.421 − 251 =
36. 36.557 − 188 =
37. 37.801 − 587 =
38. 38.556 + 467 =
39. 39.282 + 397 =
40. 40.504 − 194 =

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