Help with binary code? Sister (1st yr uni) stuck on converting, adding, understanding... any good sites?

Answer 1

it goes 128 64 32 16 8 4 2 1

When there is a 1 , you use the corresponding number. when there is a 0 you use a 0

1 0 1 0 1 0 0 0
128+0 +32+0+8+0+0+0 = 168

Answer 2

I not sure of a site. But, it a simple 1 & 0 thing and just requires practice to add, subtract etc.
Really can not find a good site on this. Maybe she could take a class to learn it.