3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 188 · 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. 1.835 − 331 =
2. 2.855 − 551 =
3. 3.575 − 205 =
4. 4.380 + 555 =
5. 5.528 + 349 =
6. 6.628 − 209 =
7. 7.704 + 303 =
8. 8.492 − 354 =
9. 9.460 − 177 =
10. 10.746 − 411 =
11. 11.546 − 183 =
12. 12.876 − 621 =
13. 13.417 − 203 =
14. 14.654 + 313 =
15. 15.766 − 396 =
16. 16.505 − 325 =
17. 17.452 − 289 =
18. 18.436 − 151 =
19. 19.152 + 239 =
20. 20.590 − 141 =
21. 21.565 − 308 =
22. 22.593 − 244 =
23. 23.779 + 204 =
24. 24.690 + 562 =
25. 25.244 + 501 =
26. 26.988 − 359 =
27. 27.236 + 683 =
28. 28.757 − 254 =
29. 29.566 − 186 =
30. 30.657 + 485 =
31. 31.182 + 425 =
32. 32.597 + 261 =
33. 33.216 + 601 =
34. 34.728 + 327 =
35. 35.131 + 144 =
36. 36.834 − 421 =
37. 37.880 − 308 =
38. 38.317 + 632 =
39. 39.496 − 263 =
40. 40.380 + 417 =

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