The CAS Registry Mumber 94055-55-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,4,0,5 and 5 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 94055-55: (7*9)+(6*4)+(5*0)+(4*5)+(3*5)+(2*5)+(1*5)=137 137 % 10 = 7 So 94055-55-7 is a valid CAS Registry Number.