syntax error: operand expected [error token is "/ "]

Question

DSKUSDPERCENT=$(($DISKUSD * 100 / $limit)) throughs error like

syntax error: operand expected (error token is "/ ") where limit=$OPTARG defined in Process command line options

here I am not able to get the value of $limit

Error: check_disk.sh: line: 119 * 100 / : syntax error: operand expected (error token is "/ ")