Evaluate the expression. \[ \frac{15 !}{11 ! 4 !} \]

Step 1 ：The given expression is a combination formula, which is often used in probability theory and combinatorics. It is usually written as C(n, k) or 'n choose k', and it represents the number of ways to choose k items from a set of n items. The formula for a combination is: \[C(n, k) = \frac{n!}{k!(n-k)!}\] where n! is the factorial of n, which is the product of all positive integers up to n.

Step 2 ：In this case, n = 15 and k = 4. So we need to calculate the factorial of 15, 11, and 4, and then substitute these values into the combination formula.

Step 3 ：Calculate the factorial of 15, which is 1307674368000.

Step 4 ：Calculate the factorial of 4, which is 24.

Step 5 ：Calculate the factorial of 11, which is 39916800.

Step 6 ：Substitute these values into the combination formula: \[C(15, 4) = \frac{1307674368000}{24 \times 39916800} = 1365.0\]

Step 7 ：Final Answer: The result of the expression \(\frac{15 !}{11 ! 4 !}\) is \(\boxed{1365}\)