The CAS Registry Mumber 13780-92-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,3,7,8 and 0 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 13780-92: (7*1)+(6*3)+(5*7)+(4*8)+(3*0)+(2*9)+(1*2)=112 112 % 10 = 2 So 13780-92-2 is a valid CAS Registry Number.