The CAS Registry Mumber 4957-86-2 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,9,5 and 7 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 4957-86: (6*4)+(5*9)+(4*5)+(3*7)+(2*8)+(1*6)=132 132 % 10 = 2 So 4957-86-2 is a valid CAS Registry Number.