BRAIN TEASERS

 

 
What's My Number?
If you divide my number by 2,3,4,5 or 6, you will find there is always a remainder of 1. But if you divide it by 11, there is no remainder. My number is less than 200. What's my number?

 

 

 

 

 

 

 

 

 
Remarkable Numbers
Seven hundred twenty (720) is a remarkable number. It can be divided evenly by many numbers (1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24, 30, 36, 40, 45, 48, 60, 72, 80, 90, 120, 144, 180, 240, 360, and 720). There are 30 different numbers in all. Can you find an even more remarkable number, less than 1,000?

 

 

 

 

 

 

 
Oranges

A grocer bought 15 dozen oranges at $0.99 a dozen. He found 15 bad oranges in the box. He sold the rest of the oranges in sacks of three.

What is the least amount that three oranges can sell for in order for the grocer to break even?

How much must three oranges sell for in order for the grocer to make an $11.00 profit?


 

 

 

 

 

 
Decimal Magic Squares

Insert the following decimals into a 3 by 3 grid like the one below to get a sum of 3 along the horizontal, vertical and diagonal axis:

0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8

     
     
     

What pattern do you notice?


 

 

 

 

 

 

 

 
Traveling

Three travelers are leaving Houston for Austin on the same day. One is traveling by car, one by train, and one by air. The round trip by car takes 300 minutes. The round trip by train takes 360 minutes. The round trip by air takes 70 minutes. How much time will elapse before all three passengers will leave Houston again at the same time?

Assume continuous round-trip activities for all three travelers.


 

 

 

 

 

 

 

 
Game of Chance

In a game of chance Susan doubled her money and then spent $5.00. In a second game of chance she tripled her money and then spent $15.00.

If she had $12.00 left how much money did Susan start with?


 

 

 

 

 

 

 

 

 
Missing Numbers

What are the missing numbers in this arrangement?

1
2
3
4
5
1
3
9
21
41
1
?
?
?
?
1
?
?
?
244769

 

 

 

 

 

 

 

 

 
Fraction Magic Squares

Insert the following fractions into the 3 by 3 grid to yield a sum of 3 3/4 along the horizontal, vertical, and diagonal axis:

1/4, 1/2, 3/4, 1, 1 1/4, 1 1/2, 1 3/4, 2, 2 1/4

What pattern do you notice?


 

 

 

 

 

 

 

 
Mathematical Boast?
Back in the year 1849, people born in 1806 were able to make an unusual mathematical boast. This unusual boast could also have been made by people in 1936 by people born in 1892. In 2025, this ususal mathematical boast can be made by individuals who were born in 1980. Given that a person was born in the 21st century, in what year will that person be able to make this unusual mathematical boast?

 

 

 

 

 

 

 

 

 
Account Balance

Marcus, Oscar, Jose, Charles, and Joel are making remarks about their own and each others bank account balances.

Marcus Joel has $729
Oscar I have $1024
Jose Oscar has $613
Charles Marcus has $571
Joel

Oscar has more than Marcus
Charles has $30 less than Jose

Remarks made by anyone whose balance is $500 or over are true, unless his account balance is perfect square. Remarks made by anyone whose balance is under $500 are flase, unless hiss account balance is a perfect cube. Find all their account balances.


 

 

 

 

 

 

 

 

 
Cross Number Puzzle
ACROSS
DOWN
1. Square of 11 down 1. A perfect cube
6. Sum of digits is 10 2. An odd number
7. A prime number 3. A prime number
8.Odd, but not prime 4. Its square equal its cube
9. This number is larger when reversed; the sum its digits is 7 5. The cube of a prime number
10. Square of product of two primes 7. When reversed this is the square of a prime number
12. A perfect cube 9. A perfect cube
11. A prime number

 

1 2 3 4 5
6 7
8 9
10 11
12

 


 

 

 

 

 

 

 

 

 
Apples
John has a crate of 256 apples. he sold 25% of them to Marci. Next he sold 25% of those remaining to George. Next he sold 25% of those to George. Next he sold 25% of those to Carla. Then he sold 25% of those remaining to Joy. Since 25% + 25% + 25% + 25% = 100%, does this mean that john sold all of his apples?

 

 

 

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