The CAS Registry Mumber 102831-75-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,2,8,3 and 1 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 102831-75: (8*1)+(7*0)+(6*2)+(5*8)+(4*3)+(3*1)+(2*7)+(1*5)=94 94 % 10 = 4 So 102831-75-4 is a valid CAS Registry Number.