The CAS Registry Mumber 374687-86-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,7,4,6,8 and 7 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 374687-86: (8*3)+(7*7)+(6*4)+(5*6)+(4*8)+(3*7)+(2*8)+(1*6)=202 202 % 10 = 2 So 374687-86-2 is a valid CAS Registry Number.