How can i average large number of multiple columns and rows in excel?

[mgh68]

i've 130000raws within column B to K spredsheet.the values are for 461values(in rows) series of time with lefting 6raws blank between every time series.
i want to take average over 500values within column B to K, for each time step(at different rows). how can i do that without taking much time?
Additional Details
it should be noted that each group of values contains series of time(in rows) and value of that variable (in column B to K, that is continued in the next group of values i.e. 500 values of a time series are not in just column B to K of a row, but in the column B to K of different rows)

[gaikwad.mm@gmail.com]

Not Clear with your requirement.

And the average can be get calculated each time the value change by putting formulas in a particular column