Question

a block of apartments have 20 floors with 20 windows on each floor how many windows does the block have all together​

Answer 1

There are 420 windows.

Explanation:

If the ground floor is part of the 20 =>

20.20=400

There are 400 windows.

If the ground floor is not part of the 20=>

20.20+20=420

There are 420 windows.