The CAS Registry Mumber 79053-15-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,9,0,5 and 3 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 79053-15: (7*7)+(6*9)+(5*0)+(4*5)+(3*3)+(2*1)+(1*5)=139 139 % 10 = 9 So 79053-15-9 is a valid CAS Registry Number.