Divide into or divide in?

[ROBINDESBOIS]

DIFFERENCE?

[laepelba]

There may be a slight difference. If you use them in context, in sentences, it will help.

"Divide into" usually means to separate a thing or a group of things into parts: I have divided my class into five groups of students. OR Divide 15 into 90.

[Rusty]

You divide a number into another number.
You divide something into halves, thirds.
You divide a square into triangles, or into rectangles.
Or, you can divide a square in half.

The first three are using into because there is a noun on both sides of the equation (both a divisor and a dividend are mentioned).
The last sentence uses in because an adverbial prepositional phrase is used instead of a noun.

I hope that makes sense.