Bash Multiplying Decimal to int

Question

I read price from user input. When i multiply the input with int like this

T=\"$((PRICE*QTY))\"|bc; gives line 272: 12.

Answer 1

First, trying to do floating-point arithmetic with bc(1) without using the -l flag is bound to give you some funny answers:

sarnold@haig:~$ bc -q
3.5 * 3.5
12.2
sarnold@haig:~$ bc -q -l
3.5 * 3.5
12.25

Second, the $((...)) is an attempt to do arithmetic in your shell; neither my bash nor dash can handle floating point numbers.

If you want to do the arithmetic in your shell, note printf(1) as well as (probably) your shell's built-in printf function. If you want to do the arithmetic in bc, note the special variable scale.