The CAS Registry Mumber 180037-68-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,0,0,3 and 7 respectively; the second part has 2 digits, 6 and 8 respectively. Calculate Digit Verification of CAS Registry Number 180037-68: (8*1)+(7*8)+(6*0)+(5*0)+(4*3)+(3*7)+(2*6)+(1*8)=117 117 % 10 = 7 So 180037-68-7 is a valid CAS Registry Number.