prepositions - divide + "into" or "in"

I knew that we use the verb "divide" with "into" preposition when we want to say to be divided into parts:

He divided a pear into two parts.

But, why in here we can also say (as I see here in Oxford):

He divided a pear in two.

Answer

As it says here, except for such phrases as divide in half and divide in two, the preposition into is used because divide emphasizes separating, breaking up or cutting up a whole into sections or parts, changing the state or form of something. When half and two are used as adjectives, the correct phrasing is divide into.

• The math teacher divided the apple in two.


• The math teacher divided the apple into two parts.


• Mother divided the pile of toys in half.


• The team’s activities were divided into half days.


• Shall we divide the project into six or seven small tasks?