The CAS Registry Mumber 75491-24-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,4,9 and 1 respectively; the second part has 2 digits, 2 and 4 respectively. Calculate Digit Verification of CAS Registry Number 75491-24: (7*7)+(6*5)+(5*4)+(4*9)+(3*1)+(2*2)+(1*4)=146 146 % 10 = 6 So 75491-24-6 is a valid CAS Registry Number.