Solution a56fc71e-38e0-4c7c-a5eb-f4c590d70380

Points: 1 pt

Let $p=221$. We check the remainder when dividing $p$ by each $i$ from $1$ to $13$.

$i$ | $p/i$ | $R$ 

$1$ | $\frac{221}{1}$ | $0$ 

$2$ | $\frac{221}{2}$ | $1$ 

$3$ | $\frac{221}{3}$ | $2$ 

$4$ | $\frac{221}{4}$ | $1$ 

$5$ | $\frac{221}{5}$ | $1$ 

$6$ | $\frac{221}{6}$ | $5$ 

$7$ | $\frac{221}{7}$ | $4$ 

$8$ | $\frac{221}{8}$ | $5$ 

$9$ | $\frac{221}{9}$ | $5$ 

$10$ | $\frac{221}{10}$ | $1$ 

$11$ | $\frac{221}{11}$ | $1$ 

$12$ | $\frac{221}{12}$ | $5$ 

$13$ | $\frac{221}{13}$ | $0$ 

Since $R=0$ for $i=13$, we have $13\mid 221$.

Final answer:
\text{221 is not prime}