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Building up a Major/Minor chord on the piano keyboard

There is a very simple way to create a Major or Minor chord on the piano keyboard. The formula needs to be remembered is "4+3"(for a major chord) or "3+4"(for a minor chord). The whole formula called "4 half steps + 3 half steps" (for a major chord) or "3 half steps + 4 half steps" (for a minor chord).

A half step is the key next to it, either above or below (left or right). It can be either white or black. For example, on the keyboard, we have 13 keys within an octave. They are:

C #C D  #D  E  F #F  G #G  A  #A  B  C 1  2  3   4  5  6  7  8  9 10  11 12  13

A half step can be a move from C to #C, or #C to D, or E to F, (F to E is also a half step but to the left) etc. That means "between the two".

When using the formula, it needs to start from the one named by the chord and include another two more keys (4 half steps +3 half steps) above it. For example, if a C major chord is our goal to build up, then we are supposed to start from the key of "C"(1), and count for four half steps above, that should be an "E"(5), and plus three half steps to "E"(5), that is a "G"(8). Therefore, the C Major chord has been built as C+E+G by using the formula 4+3.

This easy method can also be applied to any minor chord. Let's take a D Minor chord as an example. As it is mentioned before, a minor chord has to use the "3+4" principle and it needs to start from the key which is named by the chord. So D minor should be started from the key of "D"(3), and then count for 3 half steps above, which should be "F"(6), and count for another 4 half steps based on "F"(6), which comes to "A" (10) finally. So the D Minor chord has been built up as D+F+A by using the formula 3+4.

All other major and minor chords can be built up by using these two formulas.