The CAS Registry Mumber 142656-03-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,2,6,5 and 6 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 142656-03: (8*1)+(7*4)+(6*2)+(5*6)+(4*5)+(3*6)+(2*0)+(1*3)=119 119 % 10 = 9 So 142656-03-9 is a valid CAS Registry Number.