use three coins with distinct "head" and "tail" sides
for each of the six lines of the hexagram, beginning with the first (bottom) line and ending with the sixth (top) line:
toss all three coins
write down the resulting line
once six lines have been determined, the hexagram is formed

The numerical method:
assign the value 3 to each "head" result, and 2 to each "tail" result
total all the coin values
the total will be six, seven, eight or nine
determine the current line of the hexagram from this number: 6 = old yin, 7 = young yang, 8 = young yin, 9 = old yang.

An alternative is to count the "tails":
3 tails = old yin
2 tails = young yang
1 tail = young yin
0 tails = old yang

Another alternative is this simple mnemonic based on the dynamics of a group of three people. If they are all boys, for example, the masculine prevails. But, if there is one girl with two boys, the feminine prevails! So:
all tails = old yin
one tail = young yin
one head = young yang
all heads = old yang

Some purists contend that there is a problem with the three-coin method because its probabilities differ from the more ancient yarrow-stalk method. Others would argue that the yarrow stalk method was flawed, and the three coins method was actually superior. In fact, over the centuries there have even been other methods used for consulting the oracle.

If want an easier and faster way of consulting the oracle with a method that has the same probabilities as the yarrow stalk method, here's a method using two coins (with two tosses per line):
first toss of the two coins: if both are "heads," use a value of 2; otherwise, value is 3
second toss: a "head" has a value of 2, a "tail" a value of 3. Add the two values from this toss and the value from the first toss.
the sum of the three vales will be 6 (old yin), 7 (young yang), 8 (young yin), or 9 (old yang). This provides the first (bottom) line of the hexagram.

Repeat the process for each remaining line.

For this method, either rice grains, or small seeds are used.

One picks up a few seeds between the middle finger and thumb. Carefully and respectfully place them on a clean sheet of paper. Repeat this process six times, keeping each cluster of seeds in a separate pile --- each pile represents one line. One then counts the number of seeds in each cluster, starting with the first pile, which is the base line. If there is an even number of seeds, then the line is yin, otherwise the line is yang --- except if there is one seed, in which case one redoes that line.

One then asks the question again, and picks up one more cluster of seeds. Count the number of seeds you have, then keep subtracting six, until you have six seeds or less. This gives you the number of the line that specifically represent your situation. It is not a moving Line. If you do not understand your answer, you may rephrase the question, and ask it a second time.

Calendric systems

There is a component of Taoist thought which is concerned with numerological/cosmological systems. This has also been applied to the I Ching as well. The noted Chinese Neo-Confucian philosopher Shao Yung (1011-1077 CE) is the one who has done the most work in popularizing this concept and in developing/publishing oracular systems based on them. This is the most sophisticated usage of I Ching oracular systems.

The most readily accessible of these methods (the easiest to learn to do, and also to use) is called the Plum Blossom Oracle. In fact, however, there are several variants of this method. One method uses the number of brushstrokes used in writing the question along with the date and time of the inquiry. Another method simply uses the date and time without an actual question. There are other variants as well, including not using date and time at all. The resulting numbers are used to select the trigrams (in either the Early Heaven or the Later Heaven sequence), which then identify the hexagram of the answer. It is also possible to find Plum Blossom Oracle computer programs to more easily and efficiently do the calculations.

The most accurate of these calendric methods is also the most complex. This is called the Ho Map Lo Map Rational Number method (and has been published in Sherrill and Chu's "Astrology of I Ching"). It uses a very complicated series of operations with a series of tables to generate series of predictions which are entirely calendar-based.

The method set out in "Astrology of I Ching" has been reported to contain an error, leading to improper hexagrams sometimes being generated. However, the system can never produce the "missing" trigrams Li and Tui as a representation of the earthly force at a particular moment in time, since they are both assigned odd numeric values when the Later Heaven cycle of trigrams is superimposed on the so-called Magic Square of Three:

4....9....2

3....5....7

8....1....6

The earthly numbers are all even and thus the system is not flawed even though—being a composite method involving several layers - it is far from being seamless.