The CAS Registry Mumber 74827-84-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,8,2 and 7 respectively; the second part has 2 digits, 8 and 4 respectively. Calculate Digit Verification of CAS Registry Number 74827-84: (7*7)+(6*4)+(5*8)+(4*2)+(3*7)+(2*8)+(1*4)=162 162 % 10 = 2 So 74827-84-2 is a valid CAS Registry Number.