“Club Math” is the first ever student math club at Kaua‘i Community College. The club is interested in the practicality and usefulness of mathematics in everyday living. The goal is to involve the community by promoting this ideal. What follows
“Club Math” is the first ever student math club at Kaua‘i Community College. The club is interested in the practicality and usefulness of mathematics in everyday living. The goal is to involve the community by promoting this ideal. What follows is the last math puzzle printed two weeks ago followed by the answer. The club submits weekly brainteasers for the education page.
Augustus De Morgan:
“I was X years old in the year X.” Augustus De Morgan said this in the 1800s. When was he born?
Solution:
Since we know he said this in the 1800s and that was the year X, we can set up the following inequality:
1800 < X < 1900 (X is greater than 1800, but less than 1900)
In order to find his age we need only to take the square root of this inequality. In doing so, we get:
42.4264069 < X < 43.5889894
Since the question asks specifically “when was he born?” We can only use whole numbers, as squaring an irrational number will lead to another irrational number, and since there’s no such thing as the year 1850.2794, nor being 42.4264 years old, there’s only one number to choose from (43). If we square 43, we get 1849. Then, in order to find when he was born, we need to only subtract his age (43) to get the year 1806, which is subsequently the answer.
Or you could’ve used trial and error because there’s only one number whose square is in the 1800’s (43). Then subtract that from 1849 to get 1806.
This week’s
brain teaser
What number am I ?
I am a three digit number.
My tens digit is five more than my ones digit.
My hundreds digit is eight less than my tens digit.
What number am I ?