This is the ‘Unknown’ button.

Yes it is a strange name.
You can see why with this example:

1 + ? = 3

To solve the problem, you enter exactly as above:

1  +    =  3

You get the answer. The unknown is 2. And more importantly, you get the idea.

‘?’ is like the unknown quantity ‘x’ in elementary algebra.
In fact Magic Number’s solver is very much based on that.

If you never like math, you will be able to solve more problems without knowing algebra.

If you are a mathematician, you will spend less time on the mundane algebra.

Let’s do a warm up.

# Arithmetic Problems

 Problem Something × 12 = 132 Enter ? × 12 = 132 Result ? = 11

Yes we could have solved it with ‘132 ÷ 12’.
But doing so requires a bit of ‘mental’ algebra.

I had a meal for \$9.99. I also had 3 cups of coffee. The total is \$20.49. What is the price of a cup of coffee?

 Formulation Meal + 3 × Coffee = Total Enter 9.99 + 3 × ? = 20.49 Result ? = 3.5

# % Problems

The price has reduced 20%. The new price is \$180. What is the old price?

 Formulation Old price – Reduction % = New price Enter ? – 20% = 180 Result ? = 225

(For reduction, discount, decrease etc., use subtraction ‘–’.)

The old price is \$60. The new price is \$69. What is the increase in %?

 Formulation Old price + Increase % = New price Enter 60 + ? % = 69 Result ? = 15

# Algebra

Magic Number solves algebraic linear equations.

 Solve 3 ( u – 4 ) = u + 2 Enter 3 ( ? – 4 ) = ? + 2 Result ? = 7

 Solve 7 / ( 3 u + 1 ) = 4 Enter 7 / ( 3 ? + 1 ) = 4 Result ? = 0.25

In general, Magic Number tries its best to simplify the equation to the solvable form ‘a x + b = c’.

# Time

I left at 9:30 am. I took the bus and I arrived at 10:15 am.
What is my journey time?

# Ratio

HD video has width-to-height ratio 16:9.
If the width is 800, what is the height?

In other words…

As ratio is analogous to division…

Enter 16 ÷ 9 = 800 ÷ ?, you get:

## Hint

You formulate by aligning related quantities.

(You get the same result with ? ÷ 800 = 9 ÷ 16.)

# Pythagoras

You can also use the hypotenuse function  (shortcut: H).

# Trigonometry

Using the law of sines:

N-th root:

Power:

Logarithm: