The CAS Registry Mumber 101854-16-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,1,8,5 and 4 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 101854-16: (8*1)+(7*0)+(6*1)+(5*8)+(4*5)+(3*4)+(2*1)+(1*6)=94 94 % 10 = 4 So 101854-16-4 is a valid CAS Registry Number.