The CAS Registry Mumber 102850-25-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,2,8,5 and 0 respectively; the second part has 2 digits, 2 and 5 respectively. Calculate Digit Verification of CAS Registry Number 102850-25: (8*1)+(7*0)+(6*2)+(5*8)+(4*5)+(3*0)+(2*2)+(1*5)=89 89 % 10 = 9 So 102850-25-9 is a valid CAS Registry Number.