The CAS Registry Mumber 65240-50-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,5,2,4 and 0 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 65240-50: (7*6)+(6*5)+(5*2)+(4*4)+(3*0)+(2*5)+(1*0)=108 108 % 10 = 8 So 65240-50-8 is a valid CAS Registry Number.