How do you write fifteen and two hundred seven hundred-thousandths?

Answer 1

Assuming you meant:fifteenandtwenty thousand ,
seventy hundred-thousandths.

Always group by hundreds. (ex) ones, thousands, millions, etc.

Fifteen - 15
and (place decimal)
20070 - after the decimal.
So, you write it as 15.20070.
You can further simplify to 15.2007, or 1.52007×10¹.