The CAS Registry Mumber 3147-38-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 3,1,4 and 7 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 3147-38: (6*3)+(5*1)+(4*4)+(3*7)+(2*3)+(1*8)=74 74 % 10 = 4 So 3147-38-4 is a valid CAS Registry Number.