83. At a school evening, there are 12 girls and 10 boys present. In how many ways can 4 pairs for dancing be formed from them?
83. Four girls can be chosen in $C_{12}^{4}=495$ ways. Now we need to choose four boys in a specific order. This can be done in $A_{10}^{4}=5040$ ways. Finally, we get $495 \cdot 5040=2494800$ ways. We can also first choose four boys, and then four girls in a specific order. Of course, we will get the same result.