The CAS Registry Mumber 77904-02-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,9,0 and 4 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 77904-02: (7*7)+(6*7)+(5*9)+(4*0)+(3*4)+(2*0)+(1*2)=150 150 % 10 = 0 So 77904-02-0 is a valid CAS Registry Number.