The CAS Registry Mumber 137488-34-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,7,4,8 and 8 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 137488-34: (8*1)+(7*3)+(6*7)+(5*4)+(4*8)+(3*8)+(2*3)+(1*4)=157 157 % 10 = 7 So 137488-34-7 is a valid CAS Registry Number.