The CAS Registry Mumber 75226-86-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,2,2 and 6 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 75226-86: (7*7)+(6*5)+(5*2)+(4*2)+(3*6)+(2*8)+(1*6)=137 137 % 10 = 7 So 75226-86-7 is a valid CAS Registry Number.