Learn the shortcut for distinguishing between major and minor chords. All songs are based on a key center such as C major or G major. Each key has group of possible chords. Some chords are major and some are minor ,and each of the chords can be altered or embellished. The shortcut for distinguishing between major and minor chords is to remember that 1, 4, and 5 are major chords and 2, 3, and 6 are minor chords. Seven is a minor diminished chord. The second thing to remember is that all the chords in a key center are arranged alphabetically. The chords in C major are (1) C major, (2) D minor, (3) E minor), (4) F major, (5) G major, (6) A minor and (7) Bdim.
Think of major and minor scales in terms of numbers as well. Major and minor scales are diatonic scales, which means they contain eight notes separated by whole or half steps. The scale is numerical, 1-2-3-4-5-6-7-8. C major is C-D-E-F-G-A-B-C. The second octave of the scale is numbered 9-10-11-12-13 and so forth. Actually, the primary notes are 9, 11 and 13. Nine is D, 11 is F and 13 is A. Unfortunately, there isn't a shortcut for memorizing major and minor scales. You have to take the time to learn each of the scales in order to take advantage of the numbering system. It is important to know each of the scales in order to chart embellished or altered chords. The numerical number is used to signify an altered or embellished chord; 1Maj7 and 2min9 in key of C major stand for a Cmaj7 and Dmin9, respectively.
Chart out a few simple songs to develop a feel for the system. A 12-bar blues progression would be 1 1 1 1 4 4 1 1 5 4 1 1. Some musicians prefer to use slanted bars to indicate different measures. In this case the charts would look like: 1/ 1/ 1/ 1/ 4/ 4/ 1/ 1/ 5/ 4/ 1/ 1. In the key of C, the chords are C (I chord), F (4 chord) and G (5 chord). In the key of G, the chords are G (1 chord), C (4 chord) and D (5 chord). Practice playing the 12-bar sequence in various keys such as E and A. Another typical chord progression in popular music is the song "Blue Moon." The chart is 1 / 6/ 4/ 5. Remember "6" is a minor chord. In the key of C, the changes are C/ Am/ F/ G. In the key of D, the changes are D / Bm/ G/ A. A common pattern in country music is 1/ 1/ 4/ 1/ 1/ 1/ 5/ 5 the first time around, then 1/ 1/ 4/1/ 1/ 1/ 5/ 1 the second time through for the turn around.
Learn to chart more than one chord per measure. All of the examples in Step 3 use only one chord per measure. Many songs use at least two chords per measure. This can be indicated in a couple of ways. One way is to use parentheses, such as “(1 3)” to indicate C and E minor in the key of C major, or G and B minor in the key of G major. If you are using slanted lines to indicate separate measures, simply include the two chord between the slanted lines, such as “/ 1 3 /.”