The CAS Registry Mumber 344877-70-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,4,4,8,7 and 7 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 344877-70: (8*3)+(7*4)+(6*4)+(5*8)+(4*7)+(3*7)+(2*7)+(1*0)=179 179 % 10 = 9 So 344877-70-9 is a valid CAS Registry Number.