The CAS Registry Mumber 57248-71-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,7,2,4 and 8 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 57248-71: (7*5)+(6*7)+(5*2)+(4*4)+(3*8)+(2*7)+(1*1)=142 142 % 10 = 2 So 57248-71-2 is a valid CAS Registry Number.