The CAS Registry Mumber 25578-04-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,5,5,7 and 8 respectively; the second part has 2 digits, 0 and 4 respectively. Calculate Digit Verification of CAS Registry Number 25578-04: (7*2)+(6*5)+(5*5)+(4*7)+(3*8)+(2*0)+(1*4)=125 125 % 10 = 5 So 25578-04-5 is a valid CAS Registry Number.