How to concatenate a range of cells into a single cell

Transpose function can be used to create a list of values from a range of cells.  Transpose and concatenate can be used to combine a range of cells into one cell.

Step1: =concatenate(transpose(A2:A6))

Step2: highlight transpose(A2:A6) and press F9 key

Step3: Transpose formula will transform into a list of values

Step4: =CONCATENATE("11,","12,","13,","14,","15,")