The CAS Registry Mumber 18537-46-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,8,5,3 and 7 respectively; the second part has 2 digits, 4 and 6 respectively. Calculate Digit Verification of CAS Registry Number 18537-46: (7*1)+(6*8)+(5*5)+(4*3)+(3*7)+(2*4)+(1*6)=127 127 % 10 = 7 So 18537-46-7 is a valid CAS Registry Number.