Automatic numbering with sub points

[Martin Glass]

Hi,

How would I do a numbered list in Excel as per below example and have it update all of the numbers below it automatically if I just changed the top number?

AU-5112102
AU-5112102.1
AU-5112102.1.1
AU-5112102.1.2
AU-5112102.1.3
AU-5112102.1.4
AU-5112102.2
AU-5112102.2.1
AU-5112102.2.2


Martin

[JieJenn]

Assuming your "key" is located in cell A1. In A2, try this formula and fill the rest. =$D$1&"."&INT(ROW(A5)/5)+MOD(ROW(A5),5)/10