Why do you need to line up the decimal points before comparing and ordering numbers with decimals?

Because the number in decimal form has a different value based on their position from the decimal point. Every one number left of decimal point it will be valued 10 times. If you don't line them up you can compare them because they might have a different value and you will end up messing your calculation.

128/3reason being 5 and 1/3 = 16/316/3 • 2/3 = 32/31 and 1/3 = 4/3 32/3 • 4/3 this will equal 128/3