The CAS Registry Mumber 93644-61-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,3,6,4 and 4 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 93644-61: (7*9)+(6*3)+(5*6)+(4*4)+(3*4)+(2*6)+(1*1)=152 152 % 10 = 2 So 93644-61-2 is a valid CAS Registry Number.