The CAS Registry Mumber 237753-18-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,3,7,7,5 and 3 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 237753-18: (8*2)+(7*3)+(6*7)+(5*7)+(4*5)+(3*3)+(2*1)+(1*8)=153 153 % 10 = 3 So 237753-18-3 is a valid CAS Registry Number.