NOTE: The exercise instructions here are LONG — please read them all carefully. If you see an internal scrollbar to the right of these instructions, be sure to scroll down to read everything.

Write an arithmetic expression that calculates the average of 18 and 46.

You may already know that:

• the average of two numbers is their sum divided by 2
• the symbol for division is /, thus 10 divided by 5 is written as 10/5
• division has higher arithmetic precedence than addition
• parentheses (()'s) may be used to override precedence

Thus, one correct solution would be:

(18+46)/2Try it– enter the above solution and click the submit button!

Even with an exercise as simple as taking the average of 18 and 46 it is still possible to make mistakes. For example:

• we might forget to use parentheses:
  18+46/2
• or, we might use the wrong arithmetic operator:(18-46)/2

Try these and see the system feedback. Also try entering some of your own incorrect answers, and see what you get.

Again, what makes programming so interesting is that there are also MANY ways to be right. For example, we could reverse the 18 and 46 and still have a correct answer:

(46+18)/2

One of the most essential components of all learning is experimentation. Nowhere is this more true than in learning programming. Students should be encouraged to experiment with solutions even after "getting it right".

Having submitted a typical correct solution, a student might experiment with:

(18+46)/(3-1)