How to Solve Math Problems with Siri
Siri and WolframAlpha aren’t onetrick ponies. This powerful duo on your iPhone 4S can answer mathrelated questions. For example, you’re at your bank machine and you need to deposit a few checks. You have three main options: add the numbers up in your head or on paper, pull out a calculator (perhaps on your smartphone), or for the fastest solution, just ask Siri for the answer.
Here’s what a typical exchange might look like:

Press and hold the Home button.

Ask your question after you hear the familiar chime.
In this example, tell Siri the amounts of each check and ask for a total. Siri crunches the numbers for you and displays the answer on the screen.

Doublecheck the amounts you gave — you’ll see it on the screen, too — to ensure Siri heard you correctly,

If you’re all good, press the Home button to close WolframAlpha.
There are different ways to say numbers, including decimal points, if you need Siri to add it all up. For $220, for example, you can say “twotwenty” or “twohundred and twenty.” For $220.20, you can say “twotwenty point twenty,” “twotwenty dot twenty,” or “twotwenty dot two zero,” and so on. Remember, Siri is amazingly versatile.
Siri isn’t just limited to addition; you can also ask questions that involve subtraction, multiplication, and division or a combination of them all. You can say “plus” or “add,” “minus” or “take away,” “multiply” or “times,” and so on. Siri usually doesn’t have a problem figuring out what you want.
Or how about percentages and square roots? Fractions? No problem.
One of the ways to really wow your friends is to whip out your iPhone when the waiter brings your check and ask Siri to figure your tip:

Press and hold the Home button.

Ask your math question after the short chime.
For this example, ask Siri something like, “What is an 18 percent tip on $490.10 for four people?”
Within a second or two, Siri gives you the answer.

Scroll up on the results screen and you’ll see additional information.

Close Siri, pay your $22 per person, and everyone goes home feeling like it was fair (except John, who didn’t drink any wine, but that’s another story).