The CAS Registry Mumber 1148135-56-1 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,1,4,8,1,3 and 5 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 1148135-56: (9*1)+(8*1)+(7*4)+(6*8)+(5*1)+(4*3)+(3*5)+(2*5)+(1*6)=141 141 % 10 = 1 So 1148135-56-1 is a valid CAS Registry Number.