Re: more math terminology
- From: "htd" <herothatdied@xxxxxxxxx>
- Date: 23 Sep 2005 18:27:07 -0700
smw wrote:
> Since some of you are ever so kind... My son's taking some math
> enrichment thingee on the Internet via Northwestern, this week's
> assignment includes the following "hints":
>
> Perfect squares are in b5, b3, d3, b1 and c1.
> Prime numbers are in a5, c5, e5, c4, a3, c3, e3, e2 and a1.
> Triangular numbers are in d5, e4, d3, a1, e1 and c2.
> Perfect cubes are in d3 and b2.
> Powers of 2 are in b5, b2, e2 and b1.
> Palindromic numbers are in a5 and d1.
> Factors of 100 are in b5, d5, c4, b3, d3, a2 and e2.
> The median of all the numbers is in c3.
> Row 3 and column c are all odd.
> Numbers that are the same upside-down are in a5, d3 and b2.
>
> I'm unfamiliar with y'all's terminology and hence partially unable to
> elucidate the assignment. What is a "perfect square" (square of a whole
> number?) What is "a triangular number"? Which numbers are considered to
> be "the same" upside down by Anglos? 3 and 8 or 1's as well?
Technically, a "perfect square" is the square of an integer, but since
negatives square to positive, whole numbers will do. Perfect squares
are 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, etc. Perfect cubes are the
cubes of integers, which may include negative results (+-1, +-8, +-27,
etc). Powers of 2 are 1, 2, 4, 8, 16, 32, 64, etc. Triangular numbers
the result of taking the integer n and using the formula .5n(n+1)- a
good explanation is here
(http://mathworld.wolfram.com/TriangularNumber.html). Numbers that are
the same upside down... 1? 11? 55? depending on your penmanship?
Hope this helps!
htd
.
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