The CAS Registry Mumber 2753-56-2 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,7,5 and 3 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 2753-56: (6*2)+(5*7)+(4*5)+(3*3)+(2*5)+(1*6)=92 92 % 10 = 2 So 2753-56-2 is a valid CAS Registry Number.