Home Back to the Challenge Answer Try These Think About This... ResourcesTry Another Challenge  
Answer
Figure This!

The numbers of gifts received on successive days form this pattern: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55. These are triangular numbers. The total handshakes for increasing numbers of people also are triangular numbers, as are the total possibilities for double-dip ice cream cones for increasing numbers of flavors.

A sequence like 4, 7, 10, 13, …, in which you add 3 each time is an example of an arithmetic sequence.

A sequence like 1, 5, 25, 125, …, in which you multiply by 5 each time is an example of a geometric sequence.

Home · Back to the Challenge · Answer · Try These · Think About This · Resources
Try Another Challenge · Challenge Index · Math Index · Printing the Challenges · En Español
Family Corner · Teacher Corner · About Figure This! · Purchase the CD
©2004 National Council of Teachers of Mathematics
Web site and CD-ROM design/production
© 1999-2004 KnowNet Construction, Inc.