The CAS Registry Mumber 87411-50-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,7,4,1 and 1 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 87411-50: (7*8)+(6*7)+(5*4)+(4*1)+(3*1)+(2*5)+(1*0)=135 135 % 10 = 5 So 87411-50-5 is a valid CAS Registry Number.