Solve the following division problems: 4. 3 and)15 5. 4 and)16 6. 3 and)18

$$15 \div 3 = 5$$

The quotient is 5.

$$\boxed{5}$$

5. Solve $4 \overline{)16}$

$$16 \div 4 = 4$$

The quotient is 4.

$$\boxed{4}$$

6. Solve $3 \overline{)18}$

$$18 \div 3 = 6$$

The quotient is 6.

$$\boxed{6}$$