The CAS Registry Mumber 51498-56-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,1,4,9 and 8 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 51498-56: (7*5)+(6*1)+(5*4)+(4*9)+(3*8)+(2*5)+(1*6)=137 137 % 10 = 7 So 51498-56-7 is a valid CAS Registry Number.