3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 732 · 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. 1.501 + 656 =
2. 2.292 + 151 =
3. 3.613 − 332 =
4. 4.269 + 451 =
5. 5.646 + 141 =
6. 6.384 + 284 =
7. 7.571 + 534 =
8. 8.655 + 366 =
9. 9.229 + 222 =
10. 10.683 + 498 =
11. 11.764 − 128 =
12. 12.502 − 351 =
13. 13.689 + 147 =
14. 14.591 + 151 =
15. 15.160 + 242 =
16. 16.659 − 514 =
17. 17.427 − 206 =
18. 18.826 − 419 =
19. 19.986 − 358 =
20. 20.228 + 179 =
21. 21.590 + 395 =
22. 22.801 − 401 =
23. 23.405 + 196 =
24. 24.489 + 636 =
25. 25.697 − 381 =
26. 26.439 + 251 =
27. 27.199 + 427 =
28. 28.368 + 528 =
29. 29.462 − 187 =
30. 30.952 − 396 =
31. 31.976 − 474 =
32. 32.666 − 271 =
33. 33.422 − 128 =
34. 34.595 − 304 =
35. 35.680 − 312 =
36. 36.731 − 144 =
37. 37.144 + 238 =
38. 38.283 + 394 =
39. 39.532 − 129 =
40. 40.730 − 327 =

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