The CAS Registry Mumber 223492-97-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,2,3,4,9 and 2 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 223492-97: (8*2)+(7*2)+(6*3)+(5*4)+(4*9)+(3*2)+(2*9)+(1*7)=135 135 % 10 = 5 So 223492-97-5 is a valid CAS Registry Number.