The CAS Registry Mumber 52454-16-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,2,4,5 and 4 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 52454-16: (7*5)+(6*2)+(5*4)+(4*5)+(3*4)+(2*1)+(1*6)=107 107 % 10 = 7 So 52454-16-7 is a valid CAS Registry Number.