This is a actually a great trick you can do with your iPhones calculator app. It's also very easy to do.
First I'll explain what happens when you perform this trick then I'll explain how to do it. As I describe what happens imagine you're witnessing it being performed on you.
Imagine I asked you to open the calculator app on your iPhone. While you're pulling your phone out I grab a piece of paper and write a prediction on it and leave this folded paper out in full view.
I tell you we need some random numbers to multiply together. So I ask you what year you where born. Let's assume you where born in 1982. So I'd type that number in the calculator. Then hit (x) times.
Then we multiply more numbers such as the month you where born, the day of the month you where born, last 4 digits of your social security number. Multiply them all together.
Then you hit the equals key and look at the answer to the equation. I open up my prediction paper that I wrote before we started. And the number on the paper will match the answer on the calculator.
Remember you where the one that decided and typed in the numbers on the calculator. I, as the performer wasn't the one that entered them. You, as the spectator did.
Here's how it's done. This is very simple to do. I'll first explain how to do it on your own iPhone. Then I'll show you a way to do it on your friends phone.
The number should be in the 10 millions. I made this easy by making the first two numbers my age (41). Then my birthdate (2-16-71) and so on. Use any number you want but mine is easy to remember.
Then just close the app. When you want to perform the trick just open the calculator and you're ready to start adding the numbers they name and multiply them together.
How it works is after you entered your large number before hand and added the "plus zero, multiply (+ 0 X). If you plus/zero/times any number the answer will be the number you started with.
It works because you didn't click equals before you closed the calculator app.
When you perform you enter the first numbers then push the multiply key. Do this as if you're demonstrating what you want them to do. Then hand them the phone and let them multiply the rest.
So when they look back they'll notice that you couldn't have done anything funny because they where the ones that entered all the numbers and used the calculator. Not you.
To use someone else's iPhone you'll obviously have to set up their calculator by entering your number then hit plus/0/X. It only takes a moment to do. You can set up a friends phone way in advance.
To perform. Write your ending number on a piece of paper. Tell them it's your prediction. Then get some numbers from them to multiply. Make the numbers personal like birthday. Part of SS#.
It's more meaningful to them that way. And make sure you use enough numbers that they're not likely to be able to do the math in their heads.