(Actually I noticed that not everyone know it's a prime symbol; many people just type single quotation ( ' ) or escape ( ` ) key for that, which are NOT correct).
First of all, I want to claim that there is no keyboard shortcut (at least I cannot find one in Mac) for prime symbol. Option+Shift+e will give you acute accent ( ´ ), not prime ( ′ ). Did you see the difference?
OK. Here is how to:
2. Switch to the "Unicode Hex Input" when you need to type prime symbol (by clicking the Input method in the menu bar)
3. Once you are in the "Unicode Hex Input" condition, type Option+2032 for prime symbol. For double prime, it's Option+2033.
But the easiest way is to copy from this page :)
p.s. Other symbols in the Character Viewer: