Locking multiple cells (F4 key)

I'm often locking a formula in a cell so that the cell reference number doesn't change upon copying and pasting.

E.g.

=A2+5
becomes
=$A$2+5
or sometimes I choose
=A$2+5
etc.

I need to do this for around 100 different cells, and then change the lock on them.

Is there a quick way I can lock multiple cells in the same way, rather than going through each one and pressing 'F4'?

Thanks