The CAS Registry Mumber 97590-56-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,7,5,9 and 0 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 97590-56: (7*9)+(6*7)+(5*5)+(4*9)+(3*0)+(2*5)+(1*6)=182 182 % 10 = 2 So 97590-56-2 is a valid CAS Registry Number.