The CAS Registry Mumber 101512-12-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,1,5,1 and 2 respectively; the second part has 2 digits, 1 and 2 respectively. Calculate Digit Verification of CAS Registry Number 101512-12: (8*1)+(7*0)+(6*1)+(5*5)+(4*1)+(3*2)+(2*1)+(1*2)=53 53 % 10 = 3 So 101512-12-3 is a valid CAS Registry Number.