What is 5c3?

The notation ( 5C3 ) represents the number of combinations of 5 items taken 3 at a time. It can be calculated using the formula ( \binom{n}{r} = \frac{n!}{r!(n-r)!} ). For ( 5C3 ), this evaluates to ( \frac{5!}{3!(5-3)!} = \frac{5!}{3! \cdot 2!} = \frac{5 \times 4}{2 \times 1} = 10 ). Therefore, ( 5C3 = 10 ).