The CAS Registry Mumber 74582-23-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,5,8 and 2 respectively; the second part has 2 digits, 2 and 3 respectively. Calculate Digit Verification of CAS Registry Number 74582-23: (7*7)+(6*4)+(5*5)+(4*8)+(3*2)+(2*2)+(1*3)=143 143 % 10 = 3 So 74582-23-3 is a valid CAS Registry Number.