The CAS Registry Mumber 15100-52-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,5,1,0 and 0 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 15100-52: (7*1)+(6*5)+(5*1)+(4*0)+(3*0)+(2*5)+(1*2)=54 54 % 10 = 4 So 15100-52-4 is a valid CAS Registry Number.