The CAS Registry Mumber 82756-64-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,7,5 and 6 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 82756-64: (7*8)+(6*2)+(5*7)+(4*5)+(3*6)+(2*6)+(1*4)=157 157 % 10 = 7 So 82756-64-7 is a valid CAS Registry Number.