FIRST METHOD | SECOND METHOD | 1. Use confined almost exclusively | 1. Use confined exclusively to to the inscriptions. | the codices. | 2. Numerals represented by both | 2. Numerals represented by normal forms and head variants. | normal forms exclusively. | 3. Numbers expressed by using | 3. Numbers expressed by using the numerals 0 to 19, inclusive, | the numerals 0 to 19, as multipliers with the period | inclusive, as multipliers in glyphs as multiplicands. | certain positions the | fixed numerical values of | which served as | multiplicands. | 4. Numbers presented as | 4. Numbers presented as ascending or descending series. | ascending series | exclusively. | 5. Direction of reading either | 5. Direction of reading from from bottom to top, or vice | bottom to top exclusively. versa. We have seen in the foregoing pages (1) how the Maya wrote their 20 {134} numerals, and (2) how these numerals were used to express the higher numbers. The next question which concerns us is, How did they use these numbers in their calculations; or in other words, how was their arithmetic applied to their calendar? It may be said at the very outset in answer to this question, that in so far as known, _numbers appear to have had but one use throughout the Maya texts, namely, to express the time elapsing between dates_.[88] In the codices and the inscriptions alike all the numbers whose use is understood have been found to deal exclusively with the counting of time. This highly specialized use of the numbers in Maya texts has determined the first step to be taken in the process of deciphering them. Since the primary unit of the calendar was the day, all numbers should be reduced to terms of this unit, or in other words, to units of the first order, or place.[89] Hence, we may accept the following as the _first step_ in ascertaining the meaning of any number: FIRST STEP IN SOLVING MAYA NUMBERS Reduce all the units of the higher orders to units of its first, or lowest, order, and then add the resulting quantities together. The application of this rule to any Maya number, no matter of how many terms, will always give the actual number of primary units which it contains, and in this form it can be more conveniently utilized in connection with the calendar than if it were left as recorded, that is, in terms of its higher orders.