June 25, 2012
Geometry: Triangle A has sides
5, 5, and 8, and triangle B has sides 5, 5, and 6. What is the ratio of
the areas of the two triangles, A/B?
From NCTM
Answer available July 2, next puzzle
Answer to math puzzle of June 18
Number theory: Exactly 2 integers less than 100 have exactly 5 different factors. What are they, and what are the next 2 such integers LARGER than 100?
From JLS Middle School May-June Einsteins
Solution: normally composite numbers have an even number of factors. The exceptions are all squares. The simplest is 16 with 1,2,4,8,16. All the rest are odd. In fact all the numbers with exactly 5 factors are 4th powers of prime numbers: 34 = 81 (also less than 100), and 54 = 625 and 74 = 2401
©copyright 2012, Louis
Bookbinder - booky1@earthlink.net
updated 25 June 2012
From NCTM
Answer available July 2, next puzzle
Answer to math puzzle of June 18
Number theory: Exactly 2 integers less than 100 have exactly 5 different factors. What are they, and what are the next 2 such integers LARGER than 100?
From JLS Middle School May-June Einsteins
Solution: normally composite numbers have an even number of factors. The exceptions are all squares. The simplest is 16 with 1,2,4,8,16. All the rest are odd. In fact all the numbers with exactly 5 factors are 4th powers of prime numbers: 34 = 81 (also less than 100), and 54 = 625 and 74 = 2401
©copyright 2012, Louis
Bookbinder - booky1@earthlink.netupdated 25 June 2012