The CAS Registry Mumber 1575-68-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,5,7 and 5 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 1575-68: (6*1)+(5*5)+(4*7)+(3*5)+(2*6)+(1*8)=94 94 % 10 = 4 So 1575-68-4 is a valid CAS Registry Number.