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## Comment on

4-Digit Number## don't you think the 2nd, 3rd

## No, it's still 1/10 (although

No, it's still 1/10 (although it certainly seems like it might be 1/9).

However, it doesn't matter that the 1st value can't be 0. There are 10 possible values for the 2nd digit, and only 1 of them matches the 1st digit. So, the probability that the 2nd number matches the first is 1/10

## For probability approach: Why

## We're selecting an integer

We're selecting an integer from 1000 to 9999, so it's impossible for the 1st digit (the thousands digit) to be zero.

## Can we imply that the

## Yes, that would be an

Yes, that would be an equivalent model.

Great idea!

## Why isn't the probability of

## The first digit can be ANY

The first digit can be ANY digit among 1, 2, 3, 4, 5, 6, 7, 8, and 9

It doesn't matter which digit it is. What matters is that the remaining digits match the first digit.

Does that help?

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