The CAS Registry Mumber 374687-90-8 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, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 374687-90: (8*3)+(7*7)+(6*4)+(5*6)+(4*8)+(3*7)+(2*9)+(1*0)=198 198 % 10 = 8 So 374687-90-8 is a valid CAS Registry Number.