The CAS Registry Mumber 84942-51-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,9,4 and 2 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 84942-51: (7*8)+(6*4)+(5*9)+(4*4)+(3*2)+(2*5)+(1*1)=158 158 % 10 = 8 So 84942-51-8 is a valid CAS Registry Number.