While less command is showing text, we can display line numbers by typing -N and then Return.
To jump to the last line, type $
To jump to the first line, type ^

The following commands may be preceded by a number, N.
To jump to the 25th line, type 25g, or even before starting less by executing:

less +25g myfile.txt

Here, N is 25.
SPACE jumps forward one window,
b jumps back one window.
If N is specified before these, N times is done.

m , Followed by any lowercase letter, marks the current position with that letter.
' (Single quote.) Followed by any lowercase letter, returns to the position which was previously marked with that letter. Followed by another single quote, returns to the position at which the last “large” movement command was executed. Followed by a ^ or $, jumps to the beginning or end of the file respectively. Marks are preserved when a new file is examined, so the ‘ command can be used to switch between input files.