The CAS Registry Mumber 62131-47-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,2,1,3 and 1 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 62131-47: (7*6)+(6*2)+(5*1)+(4*3)+(3*1)+(2*4)+(1*7)=89 89 % 10 = 9 So 62131-47-9 is a valid CAS Registry Number.