The CAS Registry Mumber 75930-68-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,9,3 and 0 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 75930-68: (7*7)+(6*5)+(5*9)+(4*3)+(3*0)+(2*6)+(1*8)=156 156 % 10 = 6 So 75930-68-6 is a valid CAS Registry Number.