The CAS Registry Mumber 1530-50-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,5,3 and 0 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 1530-50: (6*1)+(5*5)+(4*3)+(3*0)+(2*5)+(1*0)=53 53 % 10 = 3 So 1530-50-3 is a valid CAS Registry Number.