The CAS Registry Mumber 7388-32-1 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,3,8 and 8 respectively; the second part has 2 digits, 3 and 2 respectively. Calculate Digit Verification of CAS Registry Number 7388-32: (6*7)+(5*3)+(4*8)+(3*8)+(2*3)+(1*2)=121 121 % 10 = 1 So 7388-32-1 is a valid CAS Registry Number.