The CAS Registry Mumber 38836-13-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,8,8,3 and 6 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 38836-13: (7*3)+(6*8)+(5*8)+(4*3)+(3*6)+(2*1)+(1*3)=144 144 % 10 = 4 So 38836-13-4 is a valid CAS Registry Number.