If FRIEND is coded as HUMJTK, how is CANDLE written in that code?

In alphabet letter-shift coding, each letter of a word is moved a certain number of steps forward in the alphabet to get its coded letter. Comparing a word with its given code reveals the shift used at each letter position, and applying that very same position-by-position shift to a new word decodes it in the same code.

Finding the shift from FRIEND to HUMJTK:

1. F (6th letter) shifts 2 steps forward to H (8th letter).

2. R (18th letter) shifts 3 steps forward to U (21st letter).

3. I (9th letter) shifts 4 steps forward to M (13th letter).

4. E (5th letter) shifts 5 steps forward to J (10th letter).

5. N (14th letter) shifts 6 steps forward to T (20th letter).

6. D (4th letter) shifts 7 steps forward to K (11th letter).

So the first letter shifts 2 steps, and every letter after it shifts one step more than the letter before it: 2, 3, 4, 5, 6, 7.

Applying the same rule to CANDLE:

1. C (3rd letter) shifts 2 steps forward to E (5th letter).

2. A (1st letter) shifts 3 steps forward to D (4th letter).

3. N (14th letter) shifts 4 steps forward to R (18th letter).

4. D (4th letter) shifts 5 steps forward to I (9th letter).

5. L (12th letter) shifts 6 steps forward to R (18th letter).

6. E (5th letter) shifts 7 steps forward to L (12th letter).

Reading the coded letters in order gives EDRIRL.

Checking in reverse: shifting each letter of EDRIRL backward by 2, 3, 4, 5, 6, 7 respectively returns C, A, N, D, L, E, confirming the code is correct.