The CAS Registry Mumber 109164-37-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,9,1,6 and 4 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 109164-37: (8*1)+(7*0)+(6*9)+(5*1)+(4*6)+(3*4)+(2*3)+(1*7)=116 116 % 10 = 6 So 109164-37-6 is a valid CAS Registry Number.