The CAS Registry Mumber 3710-73-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 3,7,1 and 0 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 3710-73: (6*3)+(5*7)+(4*1)+(3*0)+(2*7)+(1*3)=74 74 % 10 = 4 So 3710-73-4 is a valid CAS Registry Number.