microsoft excel - How can I auto generate date based on number of contacts in a company?

I have a 50,000 row spreadsheet with information such as company, names and dates. Every company has a starting date of 4/8/15 and successive entries in the date column (within each company) are 14 days apart. So person 1 has a date of 4/8/15 while person 2 has a date of 4/22/15 and so forth.

Does anyone know how to generate the dates automatically for each person in a company so that I won't have to do it manually?

Company            name         date
ACME USA           person 1     4/8/2015
ACME USA           person 2     4/22/2015
ACME USA           person 3     5/6/2015
ACME USA           person 4     5/20/2015
Fake Company 1     person 1     4/8/2015
Fake Company 1     person 2     4/22/2015
Fake Company 1     person 3     5/6/2015

Answer

It’s fairly easy.  Assuming that your columns are A, B, and C, your headers are in row 1, and the data start in row 2, put

=IF(A1=A2, C1+14, DATEVALUE("4/8/2015"))

into cell C2 and drag down.  It says, if the company name on this row (A2) equals the company name on the previous row (A1), then this is not the first row for this company, so we should use the date from the previous row (C1) plus 14 (days).  Otherwise, the company names are different, so this is the first row for this company, so we should use 4/8/2015.  You’ll need to format column C as “date”.