The CAS Registry Mumber 754-62-1 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 7,5 and 4 respectively; the second part has 2 digits, 6 and 2 respectively. Calculate Digit Verification of CAS Registry Number 754-62: (5*7)+(4*5)+(3*4)+(2*6)+(1*2)=81 81 % 10 = 1 So 754-62-1 is a valid CAS Registry Number.