The number halfway between $\frac{1}{12}$ and $\frac{1}{10}$ is
(A) $\frac{1}{11}$
(B) $\frac{1}{120}$
(C) $\frac{11}{60}$
(D) $\frac{11}{120}$
(E) $\frac{1}{22}$
The number halfway between two numbers is their average.

Therefore, the number halfway between $\frac{1}{10}$ and $\frac{1}{12}$ is $\frac{1}{2}\left(\frac{1}{10}+\frac{1}{12}\right)=\frac{1}{2}\left(\frac{12}{120}+\frac{10}{120}\right)=\frac{1}{2}\left(\frac{22}{120}\right)=\frac{11}{120}$.