The CAS Registry Mumber 2584-73-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,5,8 and 4 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 2584-73: (6*2)+(5*5)+(4*8)+(3*4)+(2*7)+(1*3)=98 98 % 10 = 8 So 2584-73-8 is a valid CAS Registry Number.