The CAS Registry Mumber 57434-13-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,7,4,3 and 4 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 57434-13: (7*5)+(6*7)+(5*4)+(4*3)+(3*4)+(2*1)+(1*3)=126 126 % 10 = 6 So 57434-13-6 is a valid CAS Registry Number.