$\dfrac24=\dfrac\bigstar{2}$

$\bigstar=$

• Your answer should be
• an integer, like $6$
• a simplified proper fraction, like $3/5$
• a simplified improper fraction, like $7/4$
• a mixed number, like $1\ 3/4$
• an exact decimal, like $0.75$
• a multiple of pi, like $12\ \text{pi}$ or $2/3\ \text{pi}$