aµdt = hµcµdt = average probability that a reaction R_{µ} will occur in the next time interval dt
C_{µ}dt = average probability that two reactant molecules will collide according to R_{µ} in the time interval dt
h_{µ} = total number of possible reaction combinations
e.g: Homocysteine conversion to metheonine is reaction six (R_{6}):
R_{6}: Five MTHF+Hcy→THF+Met
Assuming there is Z molecules of five MTHF
&
X molecules of Hcy:
h1 = X*Z = number of possible reaction combinations
X*Z* C_{6}dt = Probability that R_{6} will occur inthe next time interval.
Where C_{6} is the stochastic rate constant for reaction 6 
