The CAS Registry Mumber 105157-38-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,5,1,5 and 7 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 105157-38: (8*1)+(7*0)+(6*5)+(5*1)+(4*5)+(3*7)+(2*3)+(1*8)=98 98 % 10 = 8 So 105157-38-8 is a valid CAS Registry Number.