The CAS Registry Mumber 98654-16-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,8,6,5 and 4 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 98654-16: (7*9)+(6*8)+(5*6)+(4*5)+(3*4)+(2*1)+(1*6)=181 181 % 10 = 1 So 98654-16-1 is a valid CAS Registry Number.