The CAS Registry Mumber 133694-85-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,3,6,9 and 4 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 133694-85: (8*1)+(7*3)+(6*3)+(5*6)+(4*9)+(3*4)+(2*8)+(1*5)=146 146 % 10 = 6 So 133694-85-6 is a valid CAS Registry Number.