Question

Mr. SMITH had 4 daughters, each daughter had a brother...How many children does Mr. Smith have?

Answer 1

This can be an interesting riddle depending on how you perceive it! 

The use of word 'had' creates all the difference here

And the final question asks 
"How many children does Mr. Smith have"

So these riddle questions need to be looked carefully about language! 
So the answer is 0

Perhaps all the children are no longer alive now! 

Hope it helped

Answer 2

Question is -

"Mr. Smith had 4 daughters. Each daughter had a brother. How many children does Mr. Smith have?"

Answer is -

Well! If we think that 'had' be replaced with 'have', then Mr. Smith have five children.

Taking the question as a correct one, we conclude that one possibility arises. We can say that Mr. Smith has $\textbf{no children}$ now.

#MarkAsBrainliest