The CAS Registry Mumber 71929-72-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,1,9,2 and 9 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 71929-72: (7*7)+(6*1)+(5*9)+(4*2)+(3*9)+(2*7)+(1*2)=151 151 % 10 = 1 So 71929-72-1 is a valid CAS Registry Number.