The CAS Registry Mumber 75228-37-4 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 8 respectively; the second part has 2 digits, 3 and 7 respectively. Calculate Digit Verification of CAS Registry Number 75228-37: (7*7)+(6*5)+(5*2)+(4*2)+(3*8)+(2*3)+(1*7)=134 134 % 10 = 4 So 75228-37-4 is a valid CAS Registry Number.