Luis has a simple calculator that has buttons for the digits 0 through 9, each of the 4 basic operations (+, - ,*,/ ), and an '=' button. Luis pushes a digit followed by the '+' sign, followed by another digit, followed by the '-' sign, followed by another digit and then the '=' sign. How many different answers could Luis get?

Well, Luis certainly knows how to add and subtract with his calculator! Let's break it down step by step.

When Luis pushes a digit followed by the '+' sign, he performs addition. Since there are 10 digits to choose from, he has 10 options for the first number. Similarly, he has 10 options for the second number.

After that, Luis pushes the '-' sign, indicating subtraction. Again, he has 10 options for the third number.

Finally, he pushes the '=' sign to get the answer. Since addition and subtraction are binary operations, each step has only one answer. Therefore, the number of different answers Luis can get is 1.

So, no matter which digits Luis chooses, he'll always end up with just one answer. It's a bit anticlimactic, but at least it saves him from any calculator-induced confusion!