The CAS Registry Mumber 126937-45-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,9,3 and 7 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 126937-45: (8*1)+(7*2)+(6*6)+(5*9)+(4*3)+(3*7)+(2*4)+(1*5)=149 149 % 10 = 9 So 126937-45-9 is a valid CAS Registry Number.