1. Choosing Random Integer

Each of four students chooses at random one integer from 1 to 10 inclusive. What is the probability that at least 2 of them choose the same integer?

2. Originally Posted by sweeetcaroline
Each of four students chooses at random one integer from 1 to 10 inclusive. What is the probability that at least 2 of them choose the same integer?
Do you understand that there are $10^4$ ways to choose the integers?

Let's find the number of ways that no two of the same integers are chosen.
That number is $10\cdot 9\cdot 8\cdot 7$. WHY?

Then what is the number in which at least two of the same are chosen?