The CAS Registry Mumber 32638-47-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,2,6,3 and 8 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 32638-47: (7*3)+(6*2)+(5*6)+(4*3)+(3*8)+(2*4)+(1*7)=114 114 % 10 = 4 So 32638-47-4 is a valid CAS Registry Number.