The CAS Registry Mumber 910660-86-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 9,1,0,6,6 and 0 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 910660-86: (8*9)+(7*1)+(6*0)+(5*6)+(4*6)+(3*0)+(2*8)+(1*6)=155 155 % 10 = 5 So 910660-86-5 is a valid CAS Registry Number.