Which of following indicates the correct numbering style between the following pairs?

2 laptops [a] OR two laptops [b]

The correct numbering style between the following pairs is:

[a] - 2 laptops

The correct numbering style between the following pairs depends on the context in which the phrase is used.

If you are referring to the number 2 as a digit, then the correct style is "2 laptops [a]".

If you are spelling out the number with words, then the correct style is "two laptops [b]".