The CAS Registry Mumber 102990-94-3 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 0 respectively; the second part has 2 digits, 9 and 4 respectively. Calculate Digit Verification of CAS Registry Number 102990-94: (8*1)+(7*0)+(6*2)+(5*9)+(4*9)+(3*0)+(2*9)+(1*4)=123 123 % 10 = 3 So 102990-94-3 is a valid CAS Registry Number.