The CAS Registry Mumber 97961-53-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,7,9,6 and 1 respectively; the second part has 2 digits, 5 and 3 respectively. Calculate Digit Verification of CAS Registry Number 97961-53: (7*9)+(6*7)+(5*9)+(4*6)+(3*1)+(2*5)+(1*3)=190 190 % 10 = 0 So 97961-53-0 is a valid CAS Registry Number.