The CAS Registry Mumber 53347-25-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,3,3,4 and 7 respectively; the second part has 2 digits, 2 and 5 respectively. Calculate Digit Verification of CAS Registry Number 53347-25: (7*5)+(6*3)+(5*3)+(4*4)+(3*7)+(2*2)+(1*5)=114 114 % 10 = 4 So 53347-25-4 is a valid CAS Registry Number.