The CAS Registry Mumber 38819-57-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 3,8,8,1 and 9 respectively; the second part has 2 digits, 5 and 7 respectively. Calculate Digit Verification of CAS Registry Number 38819-57: (7*3)+(6*8)+(5*8)+(4*1)+(3*9)+(2*5)+(1*7)=157 157 % 10 = 7 So 38819-57-7 is a valid CAS Registry Number.