How do I let people know that I am not as young as I look and there is no need to doubt my intelligence I am short that is why this is a problem Its frustrating when people treat me like Im a child?

Here's what you can't do: You can't get people to stop making judgments based on personal appearance. Ask a tall person how many times they've been asked about the weather or their basketball careers. I once met a young woman named Bambi with platinum blonde hair who occasionally worked as a go-go dancer. She spoke in a high-pitched little girl voice as she asked me, "How can I get people to take me more seriously?" The obvious answer: Change your name, restore your natural hair color, pitch your voice lower and keep your clothes on" isn't really helpful.

And I don't know a thing about you. Are there ways that you reinforce the stereotype? Can they be avoided or altered? Dress more maturely, etc....

As for the intelligence thing, be proactive. Adopt a serious, concerned countenance. When asked what is wrong, say "My editor needs an article on Kepler's laws on orbital motion and I can't remember the third one. Do you happen to know it?"

Keep in mind that there are some (many?) things that are nobody's business. The advice columnists would tell you if anyone inquires about your personal appearance to look at them and say, "Why would you ask such a thing?"

The good news is that this will pass and it is likely that there will be a time in your life when you are grateful to look younger than your chronological age.