I'm trying write a formula to count the duplicates in a column where they
appear contiguously (adjacent to one another). Another way of putting this is
to count the number of times a number appears continuously in a column before
it changes to another number. I have Excel 2007.

Example:
ColumnA ColumnB ColumnC(answer)
0001 30 2
0001 30
0001 70 1
0001 30 2
0001 30

Your help is greatly appreciated