The CAS Registry Mumber 25576-35-6 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 6 respectively; the second part has 2 digits, 3 and 5 respectively. Calculate Digit Verification of CAS Registry Number 25576-35: (7*2)+(6*5)+(5*5)+(4*7)+(3*6)+(2*3)+(1*5)=126 126 % 10 = 6 So 25576-35-6 is a valid CAS Registry Number.