The CAS Registry Mumber 97315-42-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,7,3,1 and 5 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 97315-42: (7*9)+(6*7)+(5*3)+(4*1)+(3*5)+(2*4)+(1*2)=149 149 % 10 = 9 So 97315-42-9 is a valid CAS Registry Number.