The CAS Registry Mumber 103826-79-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,3,8,2 and 6 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 103826-79: (8*1)+(7*0)+(6*3)+(5*8)+(4*2)+(3*6)+(2*7)+(1*9)=115 115 % 10 = 5 So 103826-79-5 is a valid CAS Registry Number.