The CAS Registry Mumber 122567-51-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,2,5,6 and 7 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 122567-51: (8*1)+(7*2)+(6*2)+(5*5)+(4*6)+(3*7)+(2*5)+(1*1)=115 115 % 10 = 5 So 122567-51-5 is a valid CAS Registry Number.