The CAS Registry Mumber 50712-65-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,0,7,1 and 2 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 50712-65: (7*5)+(6*0)+(5*7)+(4*1)+(3*2)+(2*6)+(1*5)=97 97 % 10 = 7 So 50712-65-7 is a valid CAS Registry Number.