The CAS Registry Mumber 527751-13-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 5,2,7,7,5 and 1 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 527751-13: (8*5)+(7*2)+(6*7)+(5*7)+(4*5)+(3*1)+(2*1)+(1*3)=159 159 % 10 = 9 So 527751-13-9 is a valid CAS Registry Number.