Word formation – Using all letters N, D, O, E exactly once, how many meaningful 4-letter English words can be formed?

Introduction / Context:
This is the same letter set as O,N,D,E in a different order. The task is to count valid 4-letter words using all letters exactly once. It assesses quick recognition of common anagram pairs.

Given Data / Assumptions:

• Letters: {N, D, O, E}.
• Use all four; no repetition.
• Standard dictionary words only.

Concept / Approach:
The two well-known words are “DONE” and “NODE.” Other permutations (e.g., “NEOD,” “EDON”) are not accepted stand-alone words. Thus, the accepted count is two.

Step-by-Step Solution:
List possibilities and test: DONE (valid), NODE (valid), remainder invalid.Therefore, number of meaningful 4-letter words = 2.

Verification / Alternative check:
Consult any general dictionary; both entries are standard and frequent in everyday use and technical contexts (e.g., “node” in networks).

Why Other Options Are Wrong:

• None/One: Under-count.
• Three/Four: Over-count; would require counting nonwords or specialized abbreviations.

Common Pitfalls:
Accepting partial-letter 3-letter forms (e.g., “one”). The condition requires all four letters every time.

Final Answer:
Two