Question

1
3 5 7
9 11 13 15 17

What is the middle number of 20th row?

Answer 1

I don't know if there's a shorter way to solve this. This is how I got the answer.



first column is the row number; second one is the number of numbers in that row

the number of numbers in the last row is 39. This is the row with which you're going to find the middle number. This middle number is found in the 20th number in that row.

Adding all the numbers from row 1 to 19 and adding 20 to their sum, you'll get 350.

Now, odd numbers are of the form, 2n+1.
What you're asked is the 350th odd number that means you'll substitute n with 350.

Doing that, you'll get, 2(350)+1=751

That's the answer. :)