The CAS Registry Mumber 490-70-0 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,9 and 0 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 490-70: (5*4)+(4*9)+(3*0)+(2*7)+(1*0)=70 70 % 10 = 0 So 490-70-0 is a valid CAS Registry Number.