Meet Digit. Press play to watch the video.
Your mission
Digit the robot loves numbers so much that he turns every letter into one. Today you will learn his number code. Then you will use it to find out what words are worth.
- Watch Digit's video.
- Open each tab, from left to right.
- Earn four badges to unlock The Number Vault.
Take your time. If you miss a question, you get a new one, so think before you click.
My badges
Teacher note
- Built for ages 8 to 10. This is one of the easiest cipher pages, so it works as a first code lesson. Plan on 30 to 40 minutes.
- The cipher is often called A1Z26. Each letter becomes its place number in the alphabet, with dashes between the numbers.
- Word sums is the math tab. Students add up the letter values of a word, then hunt for rare words worth exactly 100. Scratch paper helps, and it is good practice in adding a string of numbers.
- Students cannot click until they get it right. A missed question swaps in a new question, and a missed sum shows the working and brings a new word.
- Words are picked at random, so neighbors will not have the same answers.
- The Number Vault is a team challenge with scratch paper. It uses codes with no dashes, number riddles, and a code where every number was doubled.
- The Number Machine and the Word Scale stay locked until the vault is open, so nobody can use them to skip the practice.
- Offline extension: students find the value of their own name, then hunt for a classmate whose name is worth more, less, or the same.
- Progress saves in the browser on this Chromebook only.
Every letter has a number
The number code is one of the simplest ciphers in the world. Count through the alphabet. A is the 1st letter, so A is 1. B is the 2nd letter, so B is 2. Keep going until you reach Z, which is 26.
Click any letter to see its number.
Swap letters for numbers
To hide a word, write the number for each letter. Put a dash between the numbers.
To read a code, go the other way. Find each number on the chart and write down its letter. When a message has more than one word, leave a space between the words.
Why the dashes matter
Some numbers have two digits. That can cause a mix-up. Look at these four digits with no dashes.
1212
Is that 1, 2, 1, 2? That spells ABAB. Is it 12 and 12? That spells LL. Is it 12, 1, 2? That spells LAB. Nobody can be sure.
With dashes, there is only one way to read it: 12-1-2 can only be LAB.
Fast to learn, fast to crack
Here is a trick for working without the chart. Remember every fifth letter. E is 5. J is 10. O is 15. T is 20. Y is 25. From there you only have to count a step or two.
The number code is great for quick notes and treasure hunts. But it is not a strong secret. Everyone knows the order of the alphabet, so there is no key for a snoop to guess.
What is a word worth?
Once letters are numbers, you can do math with words. Add up the numbers of a word to find its value.
Letters near the end of the alphabet are worth a lot. Z is worth 26 all by itself. Letters near the start are worth very little.
Word hunters love to search for hundred-point words. Those are rare words whose letters add up to exactly 100.