To express the number 97.31 in words you have to separate it into two part
"97" and "31"
97 in word form is: Ninety-seven
31 in word form is: Thirty-one
The decimal digits are placed in the tenth and hundreth positions, you have to take the last position into acount so that the number expressed in words will be
"Ninety-seven" and "thirty-one hundreth"