The CAS Registry Mumber 29902-41-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,9,9,0 and 2 respectively; the second part has 2 digits, 4 and 1 respectively. Calculate Digit Verification of CAS Registry Number 29902-41: (7*2)+(6*9)+(5*9)+(4*0)+(3*2)+(2*4)+(1*1)=128 128 % 10 = 8 So 29902-41-8 is a valid CAS Registry Number.