The CAS Registry Mumber 4771-37-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,7,7 and 1 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 4771-37: (6*4)+(5*7)+(4*7)+(3*1)+(2*3)+(1*7)=103 103 % 10 = 3 So 4771-37-3 is a valid CAS Registry Number.