The CAS Registry Mumber 18776-25-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,8,7,7 and 6 respectively; the second part has 2 digits, 2 and 5 respectively. Calculate Digit Verification of CAS Registry Number 18776-25: (7*1)+(6*8)+(5*7)+(4*7)+(3*6)+(2*2)+(1*5)=145 145 % 10 = 5 So 18776-25-5 is a valid CAS Registry Number.