For thousands of years the Maya have lived in the region that is now southern Mexico and northern Central America. The Maya were great astronomers. They devised their calendars more than 2,000 years ago. For everyday use they had a 365-day calendar. It consisted of 18 months of 20 days each, and five additional days. They also had a sacred calendar to keep track of holidays and religious observances. This calendar had 13 months of 20 days each.
The Maya built stone monuments that tell about their kings and important events. They also wrote books dealing with the sun, the moon, and the planets, especially Venus. Most of the books were destroyed by the Spanish conquerors in the sixteenth century because they considered these books to be “the work of the devil.” These writings contain many dates. Sometimes a picture of a special head indicated a particular day of the month. Figure 12a Figure 12b Figure 12c
The Maya had an interesting way of showing a period of time in their writings and stone monuments. For this purpose they used a year that had 360 days—18 months of 20 days each. The number in Figure 13 is 5 years, 13 months, 9 days.
This may seem a strange way to write a number. Here is the code for reading it:
Each dot stands for a unit. Each bar stands for five units. The position of the bars and dots is important in reading the number.
• The lowest position tells you the number of days: 5 + 4 = 9 days.
• The next position tells you the number of months: 2 × 5 + 3 = 13 months, and 13 × 20 = 260 days.
Symbol for Day One
Figure 12a
Symbol for Day Two
Figure 12b
Symbol for Day Fifteen
Figure 12c
5 years, 13 months, 5 days
Figure 13
Figure 14a
Figure 14b
Figure 14c
• The highest position tells you the number of years: 5 years, and 5 × 360 = 1,800 days.
• The total number of days is 1,800 + 260 + 9 = 2,069 days.
Why did the Maya use bars and dots to write numbers? Probably the idea came from the marketplace. People figured out prices and money by laying out twigs and pebbles. A twig equaled five pebbles. In writing, a twig became a bar and a pebble became a dot.
The Maya had names for various units of time, as shown in this table:
baktun 20 × 7,200 = 144,000
katun 20 × 360 = 7,200
tun 18 × 20 = 360
uinal 20 × 1 = 20
kin 1 = 1
Some of their calendar stones show periods of time going back to a date that we call August 13, 3114 B.C.E. in our calendar. That’s more than 5,000 years ago!
1. Calculate the number of days for the period of time in each of the three calendar stones in Figure 14. Then translate them into years, months, and days in our calendar. How will you treat leap years?
2. Teach a friend the Maya system of writing periods of time. Then write several calendar numbers for your friend to calculate.
3. Calculate the number of days in a calendar stone that shows: 2 katuns, 10 tuns, 6 uinals, 12 kins. Then draw the stone.
4. People usually started counting by using parts of their bodies, such as the ten fingers. That is why the number ten is so important in many counting systems. Why do you think the number twenty is important in the Maya system of numbers?
You may check some of the answers on page 153.
