#TradingPairs101 Here are a few reworded versions of your sentence, depending on the tone you want:

1. Neutral/Professional: #tradingpairs101

> Each eligible post must contain a minimum of 100 words and include only one hashtag or coin pair.

2. Formal:

> To qualify, each post must comprise at least 100 words and reference only one hashtag or coin pair.

3. Concise/Direct:

> Eligible posts must have 100+ words and feature just one hashtag or coin pair.

4. Friendly/Community Style:

> Make sure your post has at least 100 words and includes only one hashtag or coin pair to be eligible!

Let me know which style suits your needs—or if you'd like this adapted for a specific platform or audience.