The CAS Registry Mumber 1373648-45-3 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,3,7,3,6,4 and 8 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 1373648-45: (9*1)+(8*3)+(7*7)+(6*3)+(5*6)+(4*4)+(3*8)+(2*4)+(1*5)=183 183 % 10 = 3 So 1373648-45-3 is a valid CAS Registry Number.