The CAS Registry Mumber 77800-46-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,8,0 and 0 respectively; the second part has 2 digits, 4 and 6 respectively. Calculate Digit Verification of CAS Registry Number 77800-46: (7*7)+(6*7)+(5*8)+(4*0)+(3*0)+(2*4)+(1*6)=145 145 % 10 = 5 So 77800-46-5 is a valid CAS Registry Number.