how many children(aged under 18) are taking drugs?

I doubt you'll find a definitive answer for this, but here are a couple of places where you can try to look for information:

http://www.fedstats.gov

http://www.ask.com
Type your QUESTION in the search box. You'll probably get a screen or two that ask you to clarify or narrow the focus of your question.

thank you very much , though what it fedstats? how do you use it?

To determine the exact number of children aged under 18 who are taking drugs, we would need access to comprehensive and up-to-date data from reliable sources, such as national surveys or government reports. As an AI, I don't have access to live data, so I can't provide you with a real-time figure. However, I can guide you on how you can find this information.

1. National Surveys: Many countries conduct surveys periodically to collect data on various health issues, including drug use among children. Check if your country has conducted any recent surveys on substance abuse, as these surveys often provide data on drug use among different age groups.

2. Government Reports: Government agencies and health departments often publish reports that include statistics on substance abuse, including drug use among minors. Search for relevant reports published by your country's government, focusing on areas like public health or youth services.

3. Research Studies: Academic institutions and research organizations may also conduct studies on drug use among children. Check if there are any recent studies published in scientific journals or available on the websites of research organizations.

4. Substance Abuse Hotlines or Helplines: Some countries have anonymous hotlines or helplines dedicated to substance abuse. You could reach out to them and inquire about the general trends or statistics on drug use among minors.

Remember, getting accurate and reliable data on such sensitive topics can be challenging due to the illegal and secretive nature of drug use. Therefore, the available data may only provide estimates or trends rather than precise numbers.