So i came across this during my piano sight reading practice and I don't know how to understand it. There is a quarter note (C) with a whole note (C) right next to it. At first i thought they're just normal notes but these two are really close to each other. Also it's in 4/4 and there are 4 quarter notes plus a whole note so it doesn't add up. I don't have a teacher so I tried searching online but I can't find a mention of it anywhere. Thanks in advance.
On the face of it, it does appear to be rather a silly thing to write! Play one note for only one beat, while holding that exact same note for four!
In fact, the bass clef in that bar could have been written the same way - or the treble notes written in a similar way to the bass clef notes. Makes more sense!
However... a lot of piano music is written like this, in 'satb'. It's like there are four instruments or voices squashed into a full stave.
There's soprano top voice with stems up, alto with stems down (where possible!) on treble clef, and tenor on the bass clef, with bass under it.
That C note in question is soprano and alto combined, so the longer note wins! But because it is also part of the melody, it gets its own dot on the soprano part.
This exercise is training the isolation of fingers by fixing the thumb and index of the right hand or the thumb and pinky finger of the left hand playing whole notes.
The whole note and the first crotchet are played at the same time (1.beat) and the whole note is held while the successing crotchet are played.
So, you are right, they are not added, the problem is that they are in the same place on the same pitch. So they are notated quite close together.