Use āfor exampleā if youāre talking about something hypothetical, or that really is an example.
You convert from Celsius to Fahrenheit by multiplying by 1.8 and then adding 32. For example, 10 C =50 F.
āFor instanceā sounds a little better if you are talking about events in time.
High tech companies have been suing each other for decades. For instance, Xerox sued Apple over the Windows interface back in the 80ās.
(For example is fine here, too)