The Help for VLOOKUP() says:
Lookup_value is the value to be found in the first column of the array.
Your lookup value is the value in 'cell 1'
and you already have a table_array which links the possible text 'values' such as doz to numeric values.
So the result of VLOOKUP() is the number to divide by.
Hope this points you in the right direction.
PS check the order of the items in your table_array, and look at VLOOKUP() Help for the range_lookup parameter.