The CAS Registry Mumber 136774-19-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,6,7,7 and 4 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 136774-19: (8*1)+(7*3)+(6*6)+(5*7)+(4*7)+(3*4)+(2*1)+(1*9)=151 151 % 10 = 1 So 136774-19-1 is a valid CAS Registry Number.