# Mathematics

### Monday, March 31, 2014

#### Area of rectangle

Joe's uncle Joe said to him, "I have two plots of land. If you can tell me within 15 seconds, which one is larger, I will give it to you." Uncle Joe pulled out a stopwatch from his pocket. "If you name the smaller one, then I'll give you half of it." "One of the plots of land is 59 meters by 61... Sign in to see full entry.

### Thursday, March 27, 2014

#### distance, velocity, time puzzle

I drove 45 miles in fifty minutes. What was my average speed in miles per hour? Sign in to see full entry.

### Tuesday, March 25, 2014

Generalization of Quadratic Equation You have all seen the derivation of the quadratic formula solution to A x 2 + B x + C = 0. Divide through by A x 2 + (B/A) x + (C/A) = 0 x 2 + (B/A) x = - (C/A) Complete the square; x 2 + (B/A) x + (B/2A) 2 = (B/2A) 2 - (C/A) Take the square root; (x + (B/2A)) =... Sign in to see full entry.

#### Calculus Joke

A constant function and e^x are walking on Broadway. Then suddenly the constant function sees a differential operator approaching and runs away. So e^x follows him and asks why the hurry. "Well, you see, there's this differential operator coming this way, and when we meet, he'll differentiate me and... Sign in to see full entry.

### Saturday, March 22, 2014

#### 2+2 = 4

Here is how we know that 2 + 2 = 4. We define 2 as 1 + 1. We define 3 as 2 + 1 We define 4 as 3 + 1 Thus 4 = 3 + 1 = (2+1) + 1 = 2 + (1+1) = 2 + 2 Conclusion: 4 is 2 + 2. Sign in to see full entry.

### Tuesday, March 18, 2014

#### Verbal puzzle

Johnny's mother had three children. The first child was named April. The second child was named May. What was the third child's name? Sign in to see full entry.

### Monday, March 17, 2014

#### Three cubes into one cube

Sally has three cubes made of modeling clay. One was 3 centimeters on a side, one was 4 centimeters on a side, and one was 5 centimeters on a side. She took the three cubes and smashed them together, then re-shaped the result into one single cube. How many centimeters on a side is that one single... Sign in to see full entry.

### Friday, March 14, 2014

#### Probability question

Puzzle: On a cold, windy day, ten year old Daniel went on a short walk with his father and two uncles. All four wore hats. Only Daniel's hat was tied on. A sudden gust of wind blew off the hats of the three adults. Daniel retrieved the hats, but did not notice the differences among them. He gave the... Sign in to see full entry.

### Thursday, March 13, 2014

#### Average score of sub-group

Arithmetical riddle # 3: A third of the students in the math class are girls. On the final exam, the girl's average score exceeds the class average by 6 points. The boy's average score is how many points below the class average? The answer to the 6 number line up is: x1 x2 x3 x4 x5 x6 1 6 4 5 2 3 2... Sign in to see full entry.

### Wednesday, March 12, 2014

#### Numbers 1 through 6 line up, but not in numerical order

Arithmetical riddle #2: Numbers one through six line up for inspection. They do not line up in numerical order. The fourth number in line is the difference of the first two numbers in line. The fifth number in line is the difference of the second and third number in line. The last number in line is... Sign in to see full entry.