The CAS Registry Mumber 140221-18-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,0,2,2 and 1 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 140221-18: (8*1)+(7*4)+(6*0)+(5*2)+(4*2)+(3*1)+(2*1)+(1*8)=67 67 % 10 = 7 So 140221-18-7 is a valid CAS Registry Number.