The CAS Registry Mumber 125042-87-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,5,0,4 and 2 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 125042-87: (8*1)+(7*2)+(6*5)+(5*0)+(4*4)+(3*2)+(2*8)+(1*7)=97 97 % 10 = 7 So 125042-87-7 is a valid CAS Registry Number.