The CAS Registry Mumber 101504-49-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,1,5,0 and 4 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 101504-49: (8*1)+(7*0)+(6*1)+(5*5)+(4*0)+(3*4)+(2*4)+(1*9)=68 68 % 10 = 8 So 101504-49-8 is a valid CAS Registry Number.