A girl wrote 7 tens Instead of 7 tenths by how much was her answer wrong?

Her answer was wrong by a factor of 10².

That means it was 100 times too large.

Well, let's scope out the scale of the problem, take it step by step ...

First, we need to know the range.:

7 tens is essentially 7 times ten, or 70.

7 tenths is 7/10, or. 7

So, subtract. 7 from 70 to get the difference of 69.3, which is your answer.