The CAS Registry Mumber 90490-67-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,4,9 and 0 respectively; the second part has 2 digits, 6 and 7 respectively. Calculate Digit Verification of CAS Registry Number 90490-67: (7*9)+(6*0)+(5*4)+(4*9)+(3*0)+(2*6)+(1*7)=138 138 % 10 = 8 So 90490-67-8 is a valid CAS Registry Number.