The CAS Registry Mumber 2492-18-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,4,9 and 2 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 2492-18: (6*2)+(5*4)+(4*9)+(3*2)+(2*1)+(1*8)=84 84 % 10 = 4 So 2492-18-4 is a valid CAS Registry Number.