In PHP Version 8.0 shows error as : PHP Fatal error: Uncaught TypeError: Unsupported operand types: string * string

[Gulshan]

In PHP Version 8.0 shows error as :
PHP Fatal error:  Uncaught TypeError: Unsupported operand types: string * string 
String is as under :
$TAXVALUE= round($QNTY*($PRICE- ($PRICE*$DISC/100)),2);

In previous versions of PHP it does not show any error.

Please resolve the issue.

[requinix]

At least one of those variables is a string containing an invalid number. Find it, figure out why it isn't the number you think it is, and fix it.