The CAS Registry Mumber 26132-21-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,6,1,3 and 2 respectively; the second part has 2 digits, 2 and 1 respectively. Calculate Digit Verification of CAS Registry Number 26132-21: (7*2)+(6*6)+(5*1)+(4*3)+(3*2)+(2*2)+(1*1)=78 78 % 10 = 8 So 26132-21-8 is a valid CAS Registry Number.