Mayan numbers have any number of places, and numbers with as many as six or seven places have been identified in hieroglyphs discovered at the sites of Mayan cities.
Because the dots are worth 1 and the bars are worth 5, there should never be more than four dots in a single place. When adding Mayan numbers, every group of five dots becomes one bar.
Likewise, the maximum value of one place is 19, so that four bars, or 20, is too large a number to fit in one place. The four bars are carried and equal one dot in the next highest place.
Let's add, in Mayan, the numbers 37 and 29:
First draw a box around each of the places of the numbers so you (and I) won't get confused.
Next, put all of the elements from both numbers into a single set of places (boxes), and to the right of this new number draw a set of empty boxes corresponding to each place of the number to the left:
You are now ready to start carrying. Begin with the place that has the lowest value, just as you do with Arabic numbers. Start at the bottom place, where each dot is worth 1. There are six dots. Five dots make one bar, so draw a bar through five of the dots, leaving you with one dot which is under the four-dot limit. Put this dot into the bottom place of the empty set of boxes you just drew:
Now look at the bars in the bottom place. There are five, and the maximum number the place can hold is three. Four bars are equal to one dot in the next highest place, so draw a circle around four of the bars and an arrow up to the dots' section of the higher place. At the end of that arrow, draw a new dot. That dot represents 20 just the same as the other dots in that place.
Not counting the circled bars in the bottom place, there is one bar left. One bar is under the three-bar limit; put it under the dot in the set of empty places to the right.
Now there are only three dots in the next highest place, so draw them in the corresponding empty box.
Continued page 3
© 1994- The Math Forum at NCTM. All rights reserved.
Home || The Math Library || Quick Reference || Search || Help
Sarah Seastone Fought
4 January 1997