Added a check to throw a IllegalArguemntException before division by 0

[morri12]

Created an if statement that checks if the denominator is zero. If it is then a IllegalArgumentException is thrown with the message "Cannot divide by zero!". If the denominator is non-zero then its business as usual.

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[morri12]

Created an if statement that checks if the denominator is zero. If it is then a IllegalArgumentException is thrown with the message "Cannot divide by zero!". If the denominator is non-zero then its business as usual.