Welcome back to the Weekly Brain Potion series for the 2018-19 School Year! This year we're asking for your requests, ideas, and feedback for the series in our Request and Idea Thread available here.

We're starting off this year with a concept we've all heard of, percents.

To start us off, let's quickly run through the following calculations, giving all your answers as decimals.

- $5\% = ??$
- $5\% \times 200 = ??$
- $200\times 5\% = ??$
- $5\% + 200 = ??$
- $200 + 5\% = ??$

Even though these calculations may seem simple, let's check our answers using some calculators. We'll be using two calculators:

- the Google calculator available here which we'll call the
*Google calculator* - an alternate online calculator available here which we'll call the
*office calculator*(be sure to always click "C" and "CE" to clear your answers before the next calculation when using this calculator)

Both calculators should give us expected answers for $5\%$. Use this as a way to get comfortable with using each of the calculators.

Let's next explore questions 4) and 5). What answers do you get using the calculators? Both calculators should give you the same answers, but the answers might surprise you! (Be sure to always end with "=" when using the office calculator). Think about real world applications involving percents. Can you explain the answers given by the calculators in terms of these applications?

Finally we look at questions 2) and 3). What answers do you get using the calculators? This time the calculators might give different answers! (Again, be sure to always end with "=" when using the office calculator). Do these answers make sense? Can you explain where the answers come from?

**Please share any thoughts or questions you have below.** We'll monitor the responses and give our thoughts as well!