The piano keyboard is made up of 88 white and black keys and a pattern that repeats every 12 keys which contains 7 white keys and 5 black keys. The white keys are named A through G and the black keys are either called Sharp ( ) or Flat ( ). You use Sharp when you go up the scale and Flat when you go down the scale. For example, the key between F and G is called F Sharp or G Flat depending on which way you go. Sometimes you see two white keys together and there are two different pairs of them. They are B and C, and E and F. They too are called Sharp and Flat. For example, C Flat is B and B Sharp is C. As pointed out earlier, Standard Middle A is 440 Hertz.  In the equal-tempered chromatic scale shown in the table below, there is a definite mathematical relationship between two adjacent notes. The ratio of the frequency of the higher note and the adjacent lower note is a constant. The constant 1.059463. For example, the frequency of each note in the middle scale is mathematically related to each other as follows:

When do you use sharps?

You use sharps when you go up the scale.

When do you use flats?

When you go up the scale.
When you go down the scale.