When you enter a fraction in an unformatted cell, you'll need to enter
the = sign before the numbers. If you enter 1/2 by itself, Excel
assumes you mean to enter a date, and "helpfully" formats the cell for
you as a date. To enter the fractional amount "one half" you enter a
formula, =1/2 to have Excel represent a numerical value.

Since your cells may be inadvertently formatted as dates, you may need
to reformat them to show numeric values. You can format the output to
read as "1/2" instead of "0.5" as well.

Additionally, you can format the cells in advance as Fractions and
after that you can enter 1/2 (without the = sign), and the entry will
be numeric.