Here are links to a series of videos for Chapter 10 - Converting between different bases.
Converting whole numbers from base 7 to a base 10 (normal, decimal) number. Like Problem #1. (Three examples)
Converting whole numbers from base 10 to base 7. Like Problem #3. (Two examples)
A reminder of how to do long addition by hand. Nothing about different bases here, just an example of simple addition.
A reminder of how to do long multiplication by hand. Nothing about different bases here, just an example of simple multiplication, in case you forgot how to do it. (You'll need to remember how to do this in normal numbers first, before you try to do it in different bases).
Adding two numbers in a different base. Like Problem #5
Multiplying two numbers in a different base. Like Problem #9.
Like problem #11. If a number is written in an unknown base, how do you find the base?
Convert from base 5 to base 10. Like problem #13.
Convert from base 10 to base 5. Like problem #15. (Two examples)