Suppose the value of the different cell is in A1:
="1D8+" & A1
="""1D8+""" & A1
="'1D8+1'" & A1
Example1: text not quoted
Example2: text quoted (double quote). Input: 3 double quotes around 1D8
Example3: text quoted (single quote). Input: Double quote, followed by
single quote before 1D8, then single quote, followed by double quote.