Titration of hydrochloric acid with sodium hydroxide C0149

High School Chemistry
Titration of 25.0 ml of hydrochloric acid with sodium hydroxide, 0.400M.
Phenolophthalein indicator.
Quick revision video clip of a titration that is frequently carried out by students at school as their first introduction to this analytical technique.
Hydrochloric acid, 25.0 ml of unknown concentration was introduced into a 250ml conical flask using a volumetric pipette.
2 drops of phenolphthalein indicator were added.
Sodium hydroxide, 0.400 M was run into the hydrochloric acid from a burette until the first permanent pink colour was observed.
Initial reading on the burette 21.7 ml
Final reading 43.4 ml.
What was the concentration of the hydrochloric acid?
Unfortunately my video camera wouldn't focus close up to allow a clear image of the burette readings on the video.
One take. Sorry for the clunky camera work.
You might calculate the concentration of the hydrochloric acid to be 0.3472M on your calculator.
This is 0.347M to three significant figures.