# Math Notes

115132219018763992565095597973971522401 = 139 + 139 + 539 + 139 + 339 + 239 + 239 + 139 + 939 + 039 + 139 + 839 + 739 + 639 + 339 + 939 + 939 + 239 + 539 + 639 + 539 + 039 + 939 + 539 + 539 + 939 + 739 + 939 + 739 + 339 + 939 + 739 + 139 + 539 + 239 + 239 + 439 + 039 + 139

# One-Sided Issue The international symbol for recycling depicts a Möbius strip.

# Do Animals Have Emotions?

In 1984, a pet kitten was given to Koko, the Stanford University gorilla who communicates through sign language.

She cared for it as a baby gorilla until December of that year, when the cat escaped from her cage and was run down by a car.

When her trainers told Koko what had happened, she gave the signs for two words.

# Ahem

The statement “no statements are true unless they can be proven scientifically” cannot be proven scientifically.

# Not So Fast

31
331
3331
33331
333331
3333331
33333331

… are all prime, but 333333331 = 17 × 19607843.

# Proof That 4 Equals 3

a + b = c

4a – 3a + 4b – 3b = 4c – 3c

4a + 4b – 4c = 3a + 3b – 3c

4(a + b – c) = 3(a + b – c)

4 = 3

# Homework It’s been known since 1876 that 267-1 isn’t prime, but for decades no one knew what the factors were.

Then, at a meeting in 1903, mathematician Frank Nelson Cole gave an hourlong “lecture” in which he didn’t say a word. On one chalkboard he expanded the value of 267-1:

147,573,952,589,676,412,927

On another he wrote:

193,707,721 × 761,838,257,287

Then he multiplied those values by hand. The two boards matched. He had found the factors. Cole returned to his seat amid a standing ovation.

He later admitted that finding the factors had taken “three years of Sundays.”

# Easy as Pi

Isaac Asimov proposed this mnemonic for a famous constant:

How I want a drink, alcoholic, of course, after the heavy lectures involving quantum mechanics!

Count the letters in each word and you’ll get 3.14159265358979.