The CAS Registry Mumber 107165-59-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,7,1,6 and 5 respectively; the second part has 2 digits, 5 and 9 respectively. Calculate Digit Verification of CAS Registry Number 107165-59: (8*1)+(7*0)+(6*7)+(5*1)+(4*6)+(3*5)+(2*5)+(1*9)=113 113 % 10 = 3 So 107165-59-3 is a valid CAS Registry Number.