The CAS Registry Mumber 103779-34-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,3,7,7 and 9 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 103779-34: (8*1)+(7*0)+(6*3)+(5*7)+(4*7)+(3*9)+(2*3)+(1*4)=126 126 % 10 = 6 So 103779-34-6 is a valid CAS Registry Number.