This beginner piano lesson is all about the musical note, middle C. This note is designated C4 in scientific pitch notation because of its position as the fourth C key on an 88-key piano. It has a frequency of 261.6 Hz.
Perhaps, you already know that there are 7 natural notes in music, by the way. They are A-B-C-D-E-F-G.
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First of all let us find out where all the C’s are located on your piano or keyboard. Take a good look at the black keys on your keyboard. You will realize that they are arranged in groups of two and three. This repeats over and over. The note, C is to the immediate left of each set of two black keys. There are 8 C naturals on an 88-key piano, 6 C naturals on a 76-key, 6 C naturals on a 61-key keyboard and 5 C naturals on a 49-key keyboard.
It’s very important to find middle C because it is the starting point for many piano songs, especially for beginners. When starting to learn piano, most books make their easiest pieces start on this note. It’s also a general border for keys played with the left hand and those played with the right hand. In other words, those keys to the left of this piano key are usually played with the left hand while those to its right are usually played with the right hand.
So which of all these C notes is middle C?
It’s quite easy. This note, as the name suggests is in the middle of your 88-key piano keyboard. Well, not exactly in the middle, but close enough, and of all the C’s on your piano, it is the one nearest to the middle. Position yourself at the center of your piano. It’s the centermost C.
The following diagram shows middle C on a 49 key, 61 key, 76 key and 88 key keyboard/piano. 
On an 88-key piano, starting from the lowest note on your keyboard and moving higher, middle C is the fourth C you can count.
How about keyboards with less keys?
On a 76-key, 61-key and 49-key keyboard, it’s the third C. If you’re not sure how many keys are on your keyboard, all you have to do is count all the keys, black and white.
We can use another method to find this key. On an 88-key piano, it’s the 24th white key from the left. On a 76-key keyboard, it’s the 20th white key. On a 61-key keyboard, it’s the 15th white key. On a 49 key keyboard, it’s the 15th white key.
In music notation, middle C is the tone represented by a note on the first ledger (leger) line below the treble clef or the first ledger line above the bass clef. The following diagram shows you this note on the grand staff. You will notice that it is between the treble clef and bass clef. 
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