Explanation:
the positions to the right of the decimal point go with negative exponents of 10 :
10^-1, 10^-2, 10^-3, ...
and that is
1/10, 1/100, 1/1000, ...
so, the first position after the decimal point stands for "tenths".
and the value of the digit for tenths in 0.88 is 8.