The CAS Registry Mumber 66959-14-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,6,9,5 and 9 respectively; the second part has 2 digits, 1 and 4 respectively. Calculate Digit Verification of CAS Registry Number 66959-14: (7*6)+(6*6)+(5*9)+(4*5)+(3*9)+(2*1)+(1*4)=176 176 % 10 = 6 So 66959-14-6 is a valid CAS Registry Number.