The CAS Registry Mumber 344585-17-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,4,4,5,8 and 5 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 344585-17: (8*3)+(7*4)+(6*4)+(5*5)+(4*8)+(3*5)+(2*1)+(1*7)=157 157 % 10 = 7 So 344585-17-7 is a valid CAS Registry Number.