How many milliliters of 0.111 m hclo4 solution are needed to neutralize 50.00 ml of 0.0789 m naoh?

HClO₄ is a strong acid and NaOH is a strong base. Therefore they completely dissociate in the solution.
NaOH + HClO₄ ---> NaClO₄ + H₂O
stoichiometry of acid to base is 1:1
amount of NaOH moles reacted - 0.0789 M / 1000 mL/L x 50.00 mL
                                                   = 0.00395 mol
Amount of HClO₄  moles reacted = 0.00395 mol
Molarity of HClO₄ is 0.111 M 
Volume of HClO₄ l containing 0.111 mol -  1 L
Therefore volume of HClO₄  containing 0.00395 mol- 1/0.111 x 0.00395 = 0.0356 L
Volume of HClO₄  - 35.6 mL