The CAS Registry Mumber 75526-83-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,5,2 and 6 respectively; the second part has 2 digits, 8 and 3 respectively. Calculate Digit Verification of CAS Registry Number 75526-83: (7*7)+(6*5)+(5*5)+(4*2)+(3*6)+(2*8)+(1*3)=149 149 % 10 = 9 So 75526-83-9 is a valid CAS Registry Number.