What is the keyboard shortcut to replace drag down or double clicking the bottom right corner?

Let’s say i filled A1 to A5 with some numbers and then B1 to B5 again with some numbers, in C1 to C5 i want the sum of numbers in those adjacent cells. What can be the keyboard shortcut for it?••••••••••••••••• • There is this method my friend told me rn- copy at C1 and then go to B1 then ‘ctrl + down’ to go to B5 and then right key to get to C5, Which is also easy but any other method please?