The CAS Registry Mumber 74842-06-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,8,4 and 2 respectively; the second part has 2 digits, 0 and 6 respectively. Calculate Digit Verification of CAS Registry Number 74842-06: (7*7)+(6*4)+(5*8)+(4*4)+(3*2)+(2*0)+(1*6)=141 141 % 10 = 1 So 74842-06-1 is a valid CAS Registry Number.