Use a calculator to evaluate the expression.
-$${ } _ { 21 } \mathrm { C } _ { 4 }$$
A) 35,910
B) 5985
C) 23,940
D) 143,640

Question

Quizplus · Accepted Answer

$${ } _ { 21 } \mathrm { C } _ { 4 }$$ calculates the number of combinations of 21 items taken 4 at a time. The formula for combinations is $$C(n, k) = \frac{n!}{k!(n-k)!}$$. Plugging in 21 for $n$ and 4 for $k$, we get $$C(21, 4) = \frac{21!}{4!(21-4)!} = \frac{21!}{4!17!}$$. Calculating this gives 5985.

Use a Calculator to Evaluate the Expression 21C4{ } _ { 21 } \mathrm { C } _ { 4 }21​C4​

Use a Calculator to Evaluate the Expression ${ } _ { 21 } \mathrm { C } _ { 4 }$