The CAS Registry Mumber 85697-93-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,6,9 and 7 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 85697-93: (7*8)+(6*5)+(5*6)+(4*9)+(3*7)+(2*9)+(1*3)=194 194 % 10 = 4 So 85697-93-4 is a valid CAS Registry Number.