The CAS Registry Mumber 198994-54-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,9,8,9,9 and 4 respectively; the second part has 2 digits, 5 and 4 respectively. Calculate Digit Verification of CAS Registry Number 198994-54: (8*1)+(7*9)+(6*8)+(5*9)+(4*9)+(3*4)+(2*5)+(1*4)=226 226 % 10 = 6 So 198994-54-6 is a valid CAS Registry Number.