Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**katey****Guest**

can you tell me good web pages for maths plus can you help me with fractions the times it is really hard and i always get them wrong

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,626

Well, we like this website! (Of course)

We have some pages here that tell you how to deal with fractions. Adding, subtracting multiplying and dividing.

For example, to multiply 1/4 by 2/3 you just multiply the top bits by the bottom bits:

1/4 x 2/3 = 1x2 / 4x3 = 2/12.

2/12 can be simplified to 1/6

You can read more about this at Multiply Fractions

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

Offline

**Barker****Member**- Registered: 2005-02-10
- Posts: 2

My daughter's homework is can you write down the properties of a cube? It is a 3D cube. Is the answer 12 sides.

Offline

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,626

A 3D cube is just a simple box. So it has a top and a bottom, a front and back and a left and right side. In othe words just 6 sides. But if you count the edges, there are 12.

You can find out more here: Platonic Solids

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

Offline

**msg21252****Member**- Registered: 2005-02-12
- Posts: 1

need formula on how to figure percentages from a whole number example: total amount for item is $3500.00, Joe's 20% is included in this number. How much does Joe get?

Offline

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,626

Percentages just mean "per 100" so 20% means "20 per 100"

Your particular problem MAY be as simple as calculating 20% of 3500, (which is 20/100 x 3500 = 20 x 3500/100 = 20 x 35 = $700)

But perhaps they mean "there was a price, Joe got 20% of that, and the total is $3500"

In that case it is a little harder.

You would figure it this way: you know that $3500 = "The Unknown Price" + 20% of "The Unknown Price" = 120% of the unknow price.

And 120% is 120/100, which is really just 1.2

So, "The Unknown Price" x 1.2 = 3500

Dividing both sides by 1.2 gets:

"The Unknown Price" x 1.2 / 1.2 = 3500 / 1.2

"The Unknown Price" = 3500 / 1.2

"The Unknown Price" = 2916.67

And Joes 20% would be 20/100 * 2916.67 = 583.33

(Confirming this: 2916.67 + 583.33 = 3500)

Was that a help?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

Offline