The CAS Registry Mumber 274252-40-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,7,4,2,5 and 2 respectively; the second part has 2 digits, 4 and 0 respectively. Calculate Digit Verification of CAS Registry Number 274252-40: (8*2)+(7*7)+(6*4)+(5*2)+(4*5)+(3*2)+(2*4)+(1*0)=133 133 % 10 = 3 So 274252-40-3 is a valid CAS Registry Number.