The CAS Registry Mumber 237769-01-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,3,7,7,6 and 9 respectively; the second part has 2 digits, 0 and 1 respectively. Calculate Digit Verification of CAS Registry Number 237769-01: (8*2)+(7*3)+(6*7)+(5*7)+(4*6)+(3*9)+(2*0)+(1*1)=166 166 % 10 = 6 So 237769-01-6 is a valid CAS Registry Number.