The CAS Registry Mumber 126594-71-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,5,9 and 4 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 126594-71: (8*1)+(7*2)+(6*6)+(5*5)+(4*9)+(3*4)+(2*7)+(1*1)=146 146 % 10 = 6 So 126594-71-6 is a valid CAS Registry Number.