The CAS Registry Mumber 78371-08-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,8,3,7 and 1 respectively; the second part has 2 digits, 0 and 8 respectively. Calculate Digit Verification of CAS Registry Number 78371-08: (7*7)+(6*8)+(5*3)+(4*7)+(3*1)+(2*0)+(1*8)=151 151 % 10 = 1 So 78371-08-1 is a valid CAS Registry Number.