The CAS Registry Mumber 113648-24-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,3,6,4 and 8 respectively; the second part has 2 digits, 2 and 4 respectively. Calculate Digit Verification of CAS Registry Number 113648-24: (8*1)+(7*1)+(6*3)+(5*6)+(4*4)+(3*8)+(2*2)+(1*4)=111 111 % 10 = 1 So 113648-24-1 is a valid CAS Registry Number.