The CAS Registry Mumber 374687-85-1 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 5 respectively. Calculate Digit Verification of CAS Registry Number 374687-85: (8*3)+(7*7)+(6*4)+(5*6)+(4*8)+(3*7)+(2*8)+(1*5)=201 201 % 10 = 1 So 374687-85-1 is a valid CAS Registry Number.