I have a simple calculation to make but must enter the formula multiple
times. Is there an easy way to do this?

I am collecting time points from multiple experiments, a t = 0 point and at
fixed intervals thereafter. The number of timepoints varies between
experiments. Showing arbitrary values, my spreadsheet is organized like this
with "Expt" in cell A1:

Expt time data value Calculation Formulas
A 0 1 1.0 =C2/$C$2
A 1 2 2.0 =C3/$C$2
A 2 3 3.0 =C4/$C$2
B 0 1.5 1.0 =C5/$C$5
B 1 2 1.3 =C6/$C$5
B 3 3 2.0 =C7/$C$5
B 4 4 2.7 =C8/$C$5
C 0 1.4 1.0 =C9/$C$9
D 0 1.8 1.0 =C10/$C$10
D 1 2 1.1 =C11/$C$10


What I need to do is calculate the change in values relative to the t = 0
timepoint for each experiment. I can enter the formulas for each t = 0 point
manually and then copy to the relevant cells. Is there an easier way?