Barcode Readers - UPC-A retail barcodes

Question 1

What do they appear to look like visually?

Answer 1

Visually, a grouping of two or more adjacent bars appear as a single wide bar

Question 2

What are the right hand codes the inverse of?

Answer 2

The left hand codes

Question 3

What is the difference of black and white bars in numbers between the left and right hand codes?

Answer 3

The left hand codes all have an odd number of black bars, whereas right hand codes all have even numbers