Certificates / Logical reasoning / Coding-Decoding
Coding-Decoding: lesson, then the certificate test
Step 1: the lesson (about 1 min)
Work out the rule from the given word and its code, letter by letter, then apply it to the new word.
- Write the position of every letter of the word and of its code.
- Common rules: a fixed shift (+1, −2), the reverse alphabet (a letter and its opposite add up to 27: A↔Z, B↔Y), or the word written backwards.
- Check the rule on EVERY letter before using it.
Worked example
If CAT is coded XZG, how is DOG coded?
- C(3)→X(24), A(1)→Z(26), T(20)→G(7): each pair adds to 27, the reverse alphabet
- D(4)→W(23), O(15)→L(12), G(7)→T(20)
Answer: WLT
Watch out
- Checking only the first letter: many rules fit one letter.
Made by Shishya (AI-assisted): a general method in our own words, with our own example; no exam or platform question is copied.
Step 2: the test
- 15 questions from Shishya's checked question bank, 20 minutes. Pass mark: 11 correct.
- Scored on Shishya's server; the answers are not shown afterwards, so the test stays fair. Each attempt draws new questions.
- Free. Your first test needs no account; sign up free to take more. Your answers and score are not stored; if you pass, you choose the name to print (ages 13 and up).
- It is a Shishya completion certificate — not a university or government credential. The test is not supervised.