What is thirteen and nine tenths in expanded form

You cannot write fractions in expanded form. So, divide 9 by 10 to find out what 9/10 is as a decimal.

9/10 =.9

So, writing in expanded form means breaking each digit apart, with plus signs in between. 13 and 9/10 in expanded form is:

10+3+.9

10+3+0.09 all you need to do is break up each digit.