The CAS Registry Mumber 101409-57-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,1,4,0 and 9 respectively; the second part has 2 digits, 5 and 7 respectively. Calculate Digit Verification of CAS Registry Number 101409-57: (8*1)+(7*0)+(6*1)+(5*4)+(4*0)+(3*9)+(2*5)+(1*7)=78 78 % 10 = 8 So 101409-57-8 is a valid CAS Registry Number.