The CAS Registry Mumber 72390-46-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,3,9 and 0 respectively; the second part has 2 digits, 4 and 6 respectively. Calculate Digit Verification of CAS Registry Number 72390-46: (7*7)+(6*2)+(5*3)+(4*9)+(3*0)+(2*4)+(1*6)=126 126 % 10 = 6 So 72390-46-6 is a valid CAS Registry Number.