The CAS Registry Mumber 142605-42-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,2,6,0 and 5 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 142605-42: (8*1)+(7*4)+(6*2)+(5*6)+(4*0)+(3*5)+(2*4)+(1*2)=103 103 % 10 = 3 So 142605-42-3 is a valid CAS Registry Number.