[tex] \frac{30}{4 \frac{1}{2} } = \\ [/tex]
[tex] \frac{30}{ \frac{4 \times 2 + 1}{2} } = \\ [/tex]
[tex] \frac{30}{ \frac{9}{2} } = \\ [/tex]
[tex]30 \div \frac{9}{2} = \\ [/tex]
[tex]30 \times \frac{2}{9} = \\ [/tex]
[tex] \frac{60}{9} = \\ [/tex]
[tex] \frac{3 \times 20}{3 \times 3} = \\ [/tex]
[tex] \frac{20}{3} = \\ [/tex]
[tex]6.666[/tex]
Which is unacceptable so we can say at least 6 children got 4½ cm³ milk.