The CAS Registry Mumber 131607-07-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,1,6,0 and 7 respectively; the second part has 2 digits, 0 and 7 respectively. Calculate Digit Verification of CAS Registry Number 131607-07: (8*1)+(7*3)+(6*1)+(5*6)+(4*0)+(3*7)+(2*0)+(1*7)=93 93 % 10 = 3 So 131607-07-3 is a valid CAS Registry Number.