The CAS Registry Mumber 77414-57-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,4,1 and 4 respectively; the second part has 2 digits, 5 and 7 respectively. Calculate Digit Verification of CAS Registry Number 77414-57: (7*7)+(6*7)+(5*4)+(4*1)+(3*4)+(2*5)+(1*7)=144 144 % 10 = 4 So 77414-57-4 is a valid CAS Registry Number.