full transcript
#### From the Ted Talk by James Tanton: Can you solve the risky disk riddle?

## Unscramble the Blue Letters

You can see for yourself that any starting configuration can sum to any number from 00 to 11 with a flip of a stwich. The reason this works is related to a cnopect called parity. Parity tells you whether a given value is even or odd. In this case, the values whose parity we’re considering are the number of 1s in each digit place of our brnaiy sums. And that’s why we can say that 2 and 0, both even numbers, can be treated as eneqlutiavs. By adndig or subtracting 00, 01, 10, or 11, we can change the parity of either, both, or neither digit, and create the disk number we want.
## Open Cloze

You can see for yourself that any starting configuration can sum to any number from 00 to 11 with a flip of a **______**. The reason this works is related to a **_______** called parity. Parity tells you whether a given value is even or odd. In this case, the values whose parity we’re considering are the number of 1s in each digit place of our **______** sums. And that’s why we can say that 2 and 0, both even numbers, can be treated as **___________**. By **______** or subtracting 00, 01, 10, or 11, we can change the parity of either, both, or neither digit, and create the disk number we want.
## Solution

- adding
- equivalents
- binary
- switch
- concept

## Original Text

You can see for yourself that any starting configuration can sum to any number from 00 to 11 with a flip of a switch. The reason this works is related to a concept called parity. Parity tells you whether a given value is even or odd. In this case, the values whose parity we’re considering are the number of 1s in each digit place of our binary sums. And that’s why we can say that 2 and 0, both even numbers, can be treated as equivalents. By adding or subtracting 00, 01, 10, or 11, we can change the parity of either, both, or neither digit, and create the disk number we want.
## Frequently Occurring Word Combinations

### ngrams of length 2

collocation |
frequency |

lit disks |
3 |

corrupted disk |
3 |

binary number |
2 |

disk number |
2 |

turning switch |
2 |

## Important Words

- adding
- binary
- called
- case
- change
- concept
- configuration
- create
- digit
- disk
- equivalents
- flip
- number
- numbers
- odd
- parity
- place
- reason
- related
- starting
- subtracting
- sum
- sums
- switch
- tells
- treated
- values
- works