3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 631 · 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. 1.152 + 172 =
2. 2.141 + 501 =
3. 3.885 − 465 =
4. 4.759 + 469 =
5. 5.563 + 356 =
6. 6.477 − 171 =
7. 7.590 + 405 =
8. 8.289 + 141 =
9. 9.144 + 454 =
10. 10.679 + 174 =
11. 11.238 + 343 =
12. 12.256 + 501 =
13. 13.186 + 453 =
14. 14.682 − 539 =
15. 15.880 − 686 =
16. 16.340 + 274 =
17. 17.887 − 421 =
18. 18.180 + 454 =
19. 19.537 + 496 =
20. 20.452 − 161 =
21. 21.570 − 239 =
22. 22.621 − 318 =
23. 23.565 + 468 =
24. 24.467 + 371 =
25. 25.687 − 261 =
26. 26.719 + 321 =
27. 27.836 − 291 =
28. 28.525 − 421 =
29. 29.566 − 466 =
30. 30.209 + 341 =
31. 31.323 + 629 =
32. 32.647 + 591 =
33. 33.460 − 281 =
34. 34.551 − 252 =
35. 35.987 − 661 =
36. 36.778 − 313 =
37. 37.258 + 135 =
38. 38.855 − 454 =
39. 39.369 + 238 =
40. 40.620 + 157 =

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