The CAS Registry Mumber 21414-47-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,1,4,1 and 4 respectively; the second part has 2 digits, 4 and 7 respectively. Calculate Digit Verification of CAS Registry Number 21414-47: (7*2)+(6*1)+(5*4)+(4*1)+(3*4)+(2*4)+(1*7)=71 71 % 10 = 1 So 21414-47-1 is a valid CAS Registry Number.