A Fun Math Riddle
Posted by Chris DeMarco on Monday, July 23rd, 2007 at 10:12 pm
I hope everyone’s having a great summer, and spending plenty of time outside! This is, of course, why there haven’t been too many posts lately. But, just to break up the monotony, here’s a fun riddle I came up with:
How many two digit numbers less than 25, that end in four, are there?
Good luck!
Oh, and I figured out how to open up commenting so you can leave your guesses. I’ll reveal the answer next week.
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Well…..the obvious answer is 9.
August 20th, 2007 at 8:32 pm
You’re close, Tom! Try again.
August 20th, 2007 at 8:39 pm
lol, i meant 10
August 20th, 2007 at 8:43 pm
lolz again, i meant 11
August 20th, 2007 at 8:44 pm
You’re right!
For all of you who are wondering why that is the answer, here you are. There are 11 numbers:
-94, -84, -74. -64, -54, -44, -34, -24, -14, 14, 24
August 20th, 2007 at 8:46 pm
sorry, just stumbled across this…but what about decimals, eh? they’re technically 2 digits…right?
so:
-94, -84, -74. -64, -54, -44, -34, -24, -14, -9.4, -8.4, -7.4, -6.4, -5.4, -4.4, -3.4, -2.4, -1.4, 1.4, 2.4, 3.4, 4.4, 5.4, 6.4, 7.4, 8.4, 9.4, 14, 24
September 5th, 2007 at 6:43 pm
I guess you kinda have a good point there, Ben…great thinking! Obviously I meant whole numbers, so if I ever use this riddle again, I’ll be sure to add that in there. Thanks!
September 5th, 2007 at 7:08 pm
Well, the number of two-digit numbers that end with the digit 4 depends heavily on your number system:
Examples:
* Real Numbers: 2,4
* Rational Numbers: 2/4
* Natural Numbers: no negative numbers
* Hex: -A4
* Octal: there is no -84, -94
May 19th, 2008 at 5:21 pm