The CAS Registry Mumber 158696-50-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,8,6,9 and 6 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 158696-50: (8*1)+(7*5)+(6*8)+(5*6)+(4*9)+(3*6)+(2*5)+(1*0)=185 185 % 10 = 5 So 158696-50-5 is a valid CAS Registry Number.