The CAS Registry Mumber 15389-64-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,5,3,8 and 9 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 15389-64: (7*1)+(6*5)+(5*3)+(4*8)+(3*9)+(2*6)+(1*4)=127 127 % 10 = 7 So 15389-64-7 is a valid CAS Registry Number.