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The saponification value of a fat was determined by adding $\pu{9.0 g}$ of the fat to flask containing $\pu{50.0 cm3}$ of $\pu{1.00 M}$ ethanolic potassium hydroxide. The remaining solution was titrated with $\pu{0.50 M}$ hydrochloric acid. Calculate the saponification value of the fat, if $\pu{15.0 cm3}$ of the $\pu{0.50 M}$ hydrochloric acid were required.

My teacher has left notes to take $\pu{15 cm3}$ of $\pu{0.5 M}$ $\ce{HCl}$ as $\pu{7.5 cm3}$ of $\pu{1 M}$ $\ce{HCl}$, which I understand. What I don't understand is why the following line is followed by $\pu{42.5 cm3}$ of $\pu{1 M}$ $\ce{HCl}$ have reacted. How do you go from $7.5$ to $42.5$?

I've calculated that the saponificaiton value is $\pu{264 mg}$ using $\pu{0.0425 mol}$.

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