1. Select the cell where you want to apply the formula.
2. Type the following formula in the formula bar:
   
   
   Formula:

   =IF(FIND(".",A1)0,[b]A1[/b],"Use other formula") 

3. Press Enter.

Explanation:

The FIND function searches for a specific character or text within a cell and returns the starting position of that character or text. In this case, we are searching for a decimal point in cell A1.

If the FIND function returns a value greater than 0, it means that a decimal point was found in cell A1. In that case, the IF function returns the value of cell A1 (which contains the decimal point) in bold.

If the FIND function returns a value of 0, it means that a decimal point was not found in cell A1. In that case, the IF function returns the text "Use other formula" (you can replace this with any other formula or text that you want to use).

Note: This formula assumes that the cell contains only one decimal point. If the cell contains multiple decimal points, the formula will return an error.