The CAS Registry Mumber 158493-15-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,8,4,9 and 3 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 158493-15: (8*1)+(7*5)+(6*8)+(5*4)+(4*9)+(3*3)+(2*1)+(1*5)=163 163 % 10 = 3 So 158493-15-3 is a valid CAS Registry Number.