I am currently working on a spreadsheet that should allow me to have a
running number of a task (T), sub task (ST) and sub sub task (SST). For
instance, for T1 consists of 3 ST. ST1 has 2 SST, and ST3 has 3 SST. T2
has only 2 ST.T2 consists of 2 ST with 2SST each.

For simplification, the following is the scenario:
T1 T2
ST1 ST2 ST3 ST1 ST2
SST1 SST2 SST1 SST2 SST3 SST1 SST2 SST1 SST2

Question: I would like for T to be assigned with a numerical value e.g.
1,2,3 with the ST having 1 decimal place (dp) no. e.g. 1.1, 1.2,
3.1,3.2,3.3 and SST having a 2 dp no. 1.1.1, 1.2.1 etc.

Thanks.