The CAS Registry Mumber 11023-54-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,1,0,2 and 3 respectively; the second part has 2 digits, 5 and 4 respectively. Calculate Digit Verification of CAS Registry Number 11023-54: (7*1)+(6*1)+(5*0)+(4*2)+(3*3)+(2*5)+(1*4)=44 44 % 10 = 4 So 11023-54-4 is a valid CAS Registry Number.