"Keep in mind" is a common phrase that means "remember".
"Take in mind" isn't a phrase anyone uses, but WOULD mean "think about" or "consider".
At least he was inventive.
![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)
He's just saying that two coins with different quantities, but the same market capitalization, would have a different price per coin. When predicting a price it's best to predict the market cap and then divide by the number of coins to get the actual price prediction.
Example:
If you think STRAT should have a market cap of $100,000,000, and there are nearly 100,000,000 coins, that's $1 per coin, or about 0.00156250 BTC.
If another coin should have a market cap of $100,000,000, but only has 50,000,000 coins, that's $2 per coin, or about 0.00312500 BTC.