Triangular NumbersDate: 4/11/96 at 10:37:41 From: Anonymous Subject: Triangular Numbers What is a Triangular Number? I have tried to look it up in my brother's math book, but it's not there! I even tried my own math book too! Date: 4/14/96 at 1:13:58 From: Doctor John Subject: Re: Triangular Numbers Triangular numbers are the number of dots you need to make triangles.These are the first few triangular numbers. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 1 3 6 10 15 The way to get these numbers without drawing pictures is to add up all the numbers that come before a certain number. For example, the tenth triangular number is 1+2+3+4+5+6+7+8+9+10. Another way to get the nth triangular number (n is any number bigger than zero) is to multiply n by one more than n and then divide by 2. This comes out exactly the same. By this method, the tenth triangular number is 10*11/2 = 55. -Doctor John, The Math Forum |
Search the Dr. Math Library: |
[Privacy Policy] [Terms of Use]
Ask Dr. Math^{TM}
© 1994- The Math Forum at NCTM. All rights reserved.
http://mathforum.org/dr.math/