The CAS Registry Mumber 155974-62-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,5,9,7 and 4 respectively; the second part has 2 digits, 6 and 2 respectively. Calculate Digit Verification of CAS Registry Number 155974-62: (8*1)+(7*5)+(6*5)+(5*9)+(4*7)+(3*4)+(2*6)+(1*2)=172 172 % 10 = 2 So 155974-62-2 is a valid CAS Registry Number.