The CAS Registry Mumber 100163-72-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,0,1,6 and 3 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 100163-72: (8*1)+(7*0)+(6*0)+(5*1)+(4*6)+(3*3)+(2*7)+(1*2)=62 62 % 10 = 2 So 100163-72-2 is a valid CAS Registry Number.