The CAS Registry Mumber 68490-35-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,8,4,9 and 0 respectively; the second part has 2 digits, 3 and 5 respectively. Calculate Digit Verification of CAS Registry Number 68490-35: (7*6)+(6*8)+(5*4)+(4*9)+(3*0)+(2*3)+(1*5)=157 157 % 10 = 7 So 68490-35-7 is a valid CAS Registry Number.