What is the pH of the resulting solution when equal volumes of 0.1 M NaOH and 0.01 M HCl are mixed?

When equal volumes of 0.1 M NaOH and 0.01 M HCl are mixed, the hydroxide ion concentration is 0.1 - 0.01/2 = 0.045 M
The pOH of the solution is pOH = -log [OH⁻] = -log 0.045 = 1.35
The pH of the solution is pH = 14 - pOH = 14 - 1.35 = 12.65