Explanation
This formula relies on the CONVERT function, which can convert a number in one measurement system to another. CONVERT is fully automatic and based on "from" and "to" unit strings. As long as the units valid options in the same category (weight, distance, temperature, etc.) , CONVERT will automatically perform a conversion and return a numeric result.
To convert from Celsius to Fahrenheit, use a "C" for Celsius and an "F" for Fahrenheit like this:
=CONVERT(B5,"C","F")
Note: unit strings are case sensitive. Both the "C" and "F" must be uppercase.
Fahrenheit to Celsius
To convert from Fahrenheit to Celsius, the formula would be:
=CONVERT(B5,"F","C")
Other conversions
You can use CONVERT to convert weight, distance, time, pressure, force, energy, power, magnetism, temperature, liquid, and volume. Unit strings must be valid and in the proper case. This page shows available options in each category.