Answer: To convert the amount of $42.50 into the number of dimes, we need to divide $42.50 by the value of one dime, which is $0.10.
Dividing $42.50 by $0.10, we get:
$42.50 ÷ $0.10 = 425
This means there are 425 dimes in $42.50.
When Lexi entered the calculation into her calculator, the decimal point appeared after the last digit, giving a result of 4 2 5 0. However, to convert the result into the number of dimes, the decimal point needs to be placed between the last two digits, since there are 10 dimes in a dollar (i.e., one dime is 0.1 dollars).
Therefore, the answer is:
425.0 dimes.