The CAS Registry Mumber 137910-35-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,7,9,1 and 0 respectively; the second part has 2 digits, 3 and 5 respectively. Calculate Digit Verification of CAS Registry Number 137910-35: (8*1)+(7*3)+(6*7)+(5*9)+(4*1)+(3*0)+(2*3)+(1*5)=131 131 % 10 = 1 So 137910-35-1 is a valid CAS Registry Number.