3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 773 · 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. 1.583 + 153 =
2. 2.875 − 421 =
3. 3.904 − 305 =
4. 4.802 − 541 =
5. 5.565 − 231 =
6. 6.479 + 451 =
7. 7.469 − 113 =
8. 8.418 − 208 =
9. 9.575 − 181 =
10. 10.509 − 256 =
11. 11.602 − 489 =
12. 12.522 − 233 =
13. 13.379 + 147 =
14. 14.480 − 311 =
15. 15.405 + 631 =
16. 16.383 + 314 =
17. 17.978 − 369 =
18. 18.712 + 531 =
19. 19.908 − 173 =
20. 20.615 + 127 =
21. 21.415 − 136 =
22. 22.474 − 362 =
23. 23.206 + 196 =
24. 24.699 − 581 =
25. 25.894 − 756 =
26. 26.755 − 408 =
27. 27.652 + 304 =
28. 28.606 − 189 =
29. 29.606 − 184 =
30. 30.227 + 151 =
31. 31.415 + 244 =
32. 32.733 + 396 =
33. 33.181 + 578 =
34. 34.416 − 224 =
35. 35.950 − 726 =
36. 36.564 − 217 =
37. 37.437 − 228 =
38. 38.205 + 112 =
39. 39.402 + 544 =
40. 40.133 + 449 =

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