The CAS Registry Mumber 100101-48-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,0,1,0 and 1 respectively; the second part has 2 digits, 4 and 8 respectively. Calculate Digit Verification of CAS Registry Number 100101-48: (8*1)+(7*0)+(6*0)+(5*1)+(4*0)+(3*1)+(2*4)+(1*8)=32 32 % 10 = 2 So 100101-48-2 is a valid CAS Registry Number.