The CAS Registry Mumber 102998-58-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,2,9,9 and 8 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 102998-58: (8*1)+(7*0)+(6*2)+(5*9)+(4*9)+(3*8)+(2*5)+(1*8)=143 143 % 10 = 3 So 102998-58-3 is a valid CAS Registry Number.