let statement in bash

let is a built-in command in bash used for evaluating arithmetic expressions.
Unlike other arithmetic evaluation and expansion commands, let is a simple command with its own environment.
The let command also allows for arithmetic expansion.

let "var1 = 6" "var2 = 2" "var3=var1+var2"; echo $var3

let only works with expressions that contain integers. The command does not support floating-point numerals.