The CAS Registry Mumber 122431-57-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,2,4,3 and 1 respectively; the second part has 2 digits, 5 and 7 respectively. Calculate Digit Verification of CAS Registry Number 122431-57: (8*1)+(7*2)+(6*2)+(5*4)+(4*3)+(3*1)+(2*5)+(1*7)=86 86 % 10 = 6 So 122431-57-6 is a valid CAS Registry Number.