The CAS Registry Mumber 65054-23-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,5,0,5 and 4 respectively; the second part has 2 digits, 2 and 3 respectively. Calculate Digit Verification of CAS Registry Number 65054-23: (7*6)+(6*5)+(5*0)+(4*5)+(3*4)+(2*2)+(1*3)=111 111 % 10 = 1 So 65054-23-1 is a valid CAS Registry Number.