9 | Number Detective . 5

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Hey there! I'm Chychy.
Welcome to Number Detective.

My beat is the city streets. The job is to bring you the best numbers we can find out there. Then share all sorts of cool stuff about them with you.


9 is an odd number. Not like the weird sort of odd, but just plain odd. See numbers come in two types - odd and even.

Even numbers are evenly divisible by 2 - that is they can be divided by 2 without a remainder. For example 24 / 2 = 12. But 25 / 2 = 12.5. The .5 (or 1/2) is the remainder, and shows that 25 is an odd number.

7 | Number Detective . 4

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Hey there! I'm Chychy.
Welcome to Number Detective.

My beat is the city streets. The job is to bring you the best numbers we can find out there. Then share all sorts of cool stuff about them with you.


7 is a big number. Not big like large, but you know big like important. 7 days in a week, 7 seas, the 7th inning stretch at a Sox game (hotdog!) and of course 7th grade where I'm at now. I found this 7 in Paisley Park, a really cool street near Fields Corner in Dorchester.

7 always brings a smile to my face. Maybe because it's a happy number. Do you remember about happy numbers from when we found the number 44? You square each digit in the number (multiply it by itself) - for 7 there's just a single digit of course - add them together and repeat the process. In a few steps happy number will soon reduce to 1. An unhappy number will just keep like running around in circles chasing its tail but never reaching 1. Here's how it goes for 7 - and it doesn't even take 7 steps!

7
49 - 7 ² (7x7 = 49)
97 - 4 ² + 9 ² (4x4 + 9x9 = 97)
130 - 9 ² + 7 ² (9x9 + 7x7 = 130)
10 - 1 ² + 3 ² (1x1 + 3x3 = 10)
1 - 1 ² + 0 ² (1x1 + 0x0 = 1)

7 is also a prime number. A prime is any number that can only be evenly divided (with no remainder) by 1 and itself. The first 7 primes are 2, 3, 5, 7, 11, 13 and 17. 1 - because 1 and 'itself' are the same - is not considered a prime. So 7 is a prime because it can only be evenly divided by 1 and 7. This is unlike, say 12, which can be divided by 1, 2, 3, 4, 6 and 12. 12 is like way divisible. No one has ever figured out any pattern in the occurrence of prime numbers. It's a big mystery. But the Number Detective is on it and will get back to you.

Image ... The number 7. Dorchester, Mass.

17 | Number Detective . 2

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Hey there! I'm Chychy.
Welcome to Number Detective.

My beat is the city streets. The job is to bring you the best numbers we can find out there. Then share all sorts of cool stuff about them with you.

Wow. This is a really old looking number, isn't it? But it's only 17! I found it above a door of a church on Hanover Street in the North End. That's the Italian part of Boston.

17 has some mysteries about it, one of which is that it's the least random number. A random number is any number that just pops into your head.

Try this on your friends, the more the better - simply ask them to pick a number between 1 and 20. Write down all the answers then look at how many times each number was chosen. You might find out, as many people do, that 17 comes out way, way ahead.

That's surprising because each number should have an equal chance of being chosen, therefore making it appear about 5% (1/20th) of the time. Some tests, however, show 17 appearing almost 20% of the time - 4 times the expected rate! A huge difference.

No one really knows why 17 is the least-random random number. But the Number Detective will keep looking into it.

44 | Number Detective . 1

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Hey there! I'm Chychy.
Welcome to Number Detective.

My beat is the city streets. The job is to bring you the best numbers we can find out there. Then share all sorts of cool stuff about them with you.


Our first number is 44. I found it at the entrance to the musician's union hall on St. Botolph Street in the South End. It's funny how the number 44 looks all new and shiny but the wreath around it is all old and crumbly.

44 is a happy number! Did you know that there are happy :) and unhappy :( numbers? Me neither until I became a number detective. Here's how it works.

Take one of the digits in the number and square it - that is, multiply it by itself. Do the same with the other digits (if any), then add the squared numbers together. Repeat the process using that result.

If this process ends in 1 you have a happy number on your hands. This is the way we figured out that 44 is happy :).

16 (4x4) + 16 (4x4) = 32

9 (3x3) + 4 (2x2) = 13

1 (1x1) + 9 (3x3) = 10

1 (1x1) + 0 (0x0) = 1

If the sequence doesn't end in 1 it will just keep circling round and round like a lost puppy but never land on 1. That's an unhappy number.

Here are the first 100 happy numbers.
1, 7, 10, 13, 19, 23, 28, 31, 32, 44, 49, 68, 70, 79, 82, 86, 91, 94, 97, 100.

Fun fact for 44
In 44 AD - XLIV in Roman numerals - Rome, led by the emperor Claudius, invaded and occupied southeast England.