What is the pH of a 10 mL solution of 100 M NaOH after addin

What is the pH of a 10 mL solution of .100 M NaOH after adding 1.0 mL of 0.100 mL HCl?

Please explain to me how to do this calculation and a calculation like this... for example, if 2.00 mL of HCl was added, 3.0 mL of HCl added, etc.

both acid and bases are strong and dissociate completely to give H+ and OH- ions,

moles of OH- = (10/1000) x 0.1 = 0.001(moles= Molarity x vol in liters)

moles of HCl = ( 1/1000) x0.1= 0.0001,

net OH- moles after neutralisation = ( 0.001-0.0001) = 0.0009, total vol = (10+1)/1000 = 0.011

[OH-] = (0.0009)/(0.011) = 0.0818 , pOH = -log[OH-] = -log(0.0818) = 1.087,

pH =14-0.818 = 12.912,

now if HCl of 5ml is added,

moles of H+ = (0.005x0.1) = 0.0005,

net [OH-] = (0.001-0.0005)/(0.01+0.005) = 0.033, pOH = -log(0.033) = 1.48, pH = 12.52,

now let HCl vol added = 12 ml,

now H+ moles = 0.012x0.1=0.0012,

H+ is excess, so excess H+ = (0.0012-0.001) = 0.0002,

[H+] = (0.0002/0.01+0.012) = 0.009, pH = -log(0.009) = 2.04