The CAS Registry Mumber 41547-66-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,1,5,4 and 7 respectively; the second part has 2 digits, 6 and 6 respectively. Calculate Digit Verification of CAS Registry Number 41547-66: (7*4)+(6*1)+(5*5)+(4*4)+(3*7)+(2*6)+(1*6)=114 114 % 10 = 4 So 41547-66-4 is a valid CAS Registry Number.