The CAS Registry Mumber 90826-15-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,8,2 and 6 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 90826-15: (7*9)+(6*0)+(5*8)+(4*2)+(3*6)+(2*1)+(1*5)=136 136 % 10 = 6 So 90826-15-6 is a valid CAS Registry Number.