The CAS Registry Mumber 107610-56-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,7,6,1 and 0 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 107610-56: (8*1)+(7*0)+(6*7)+(5*6)+(4*1)+(3*0)+(2*5)+(1*6)=100 100 % 10 = 0 So 107610-56-0 is a valid CAS Registry Number.