The easiest way is to consult a circle of fifths. As a band director, I require my students to keep one with them in their folder.
The second simple method is this. C has 0 flats, memorize that. Again, memorize that F has 1 flat.
Finally. After that, the name of the key signature will be the penultimate flat (that is the second to the last flat in the key signature.)
As an example, if there are 4 flats in your key signature they are: Bb Eb Ab and Db. They will always be listed in that order. Ab is the penultimate, and thusly this would be the key of Ab.
None. No key signature contains a mix of flats and sharps.
The key with three flats (Bb, Eb, Ab) is the key of Eb.
There are no sharps or flats in the key signature of C Major.
It's C major if there are no flats or sharps in the key signature.no sharps and flatsThere are no sharps or flats in the key signature of C Major.
No key signature has two of the same flat or sharp.
There can be a total of seven flats (or sharps) in a key signature.
A key signature, accidentals, a piece of music.
None. No key signature contains a mix of flats and sharps.
The key with three flats (Bb, Eb, Ab) is the key of Eb.
There are no sharps or flats in the key signature of C Major.
It's C major if there are no flats or sharps in the key signature.no sharps and flatsThere are no sharps or flats in the key signature of C Major.
4 sharps.
No key signature has two of the same flat or sharp.
A flat major and its relative minor are key signatures with four flats.
If there are 4 flats in the key signature it means the key is either Ab Major or F minor.
C major.
The key signature will consist of two flats: Bb, and Eb.