Calculator activitity for 2nd grade

I would like to know a simple activity that i could do with a grade 2 student, which involves using the calculator.

Here are a few ideas. Hopefully they are of help.

Add or subtract the same number repeated times.

For example, start with 10, subtract 1 repeated times and see how it goes to the negative numbers.

Start with any 2-digit number and add 100 repeated times. Or start with a 3-digit number and subtract 50 or 100 repeated times.

Here's a game: Player 1 chooses a 2-digit number. Player 2 predicts how many times you can subtract 10 before the number becomes negative. Then this is checked with calculator. If player 2 was right, he gets a point. Play till a predetermined amount of points.

Or, use adding. Player 1 chooses a three-digit number, and player 2 has to predict how many times you can add 100 to it before the result is more than 1000. Then check with calculator.

Readers, feel free to submit more ideas in the comments.