The CAS Registry Mumber 181524-65-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,1,5,2 and 4 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 181524-65: (8*1)+(7*8)+(6*1)+(5*5)+(4*2)+(3*4)+(2*6)+(1*5)=132 132 % 10 = 2 So 181524-65-2 is a valid CAS Registry Number.