The most common reasons for this are entering dollar signs or commas in your solution value. The number checker won't accept non-numerical characters (even though these two seem perfectly reasonable). Leave these out and you should be all set.

The site is designed so that solutions are the same you would get using a spreadsheet or performing the manual calculations without any intermediate rounding. Note that the Solutions (Manual) section of quiz and drill exercise solutions shows intermediate rounding purely for presentation purposes. My strong advice is to use spreadsheets to generate solutions because this is the tool you will use most often in your quantitative first year core coursework.

There is a backup set of narrated lectures that students can switch to if high student traffic causes performance problems.

To switch from the main version to the backup, click the standard Narrated Lecture link from the Teaching Materials section of a given topic, switch Tutorials to TutorialsBackup in the address, and refresh your browser.

For example, the standard narrated lecture link in the Accounting Connections topic is:

http://www.mbamath.com/Tutorials/Statement%20Connections/Present/player.html

The backup version is:

http://www.mbamath.com/TutorialsBackup/Statement%20Connections/Present/player.html

We haven't seen this in a long time but we leave this Q&A in case it recurs on certain hardware/software setups. A workaround when the problem is persistent has been to type the number of the next exercise desired in the box between the Previous and Next buttons and then to hit Enter on the keyboard. Or click Last and work backwards. There should be no difference but we are letting you know that the workarounds helped at least one user who had persistent trouble with the Next button between exercises 2 and 3 of the TVM Annual quiz.