Archive for February, 2010

Prime and composite numbers

Why on earth do you need  to know about prime and composite numbers? Fractions! Work with fractions becomes much easier if you recognize prime and composite numbers. It helps you know if a fraction needs to be simplified.

Let’s Get Started

Here are some of the terms you will encounter when working with numbers.

Factor – A number that is multiplied by another number to find a product

2 and 3 are factors of 6, because 2×3 = 6.

Prime number – A number with only two factors, itself and 1.

7 is prime because its only factor are 1 and 7.
1×7 = 7

Composite number – A number with more than two factors.

6 is a composite number because 1, 2, 3, and 6 are all factor of 6.
1 x 6 = 6        2 x 3 = 6

Reading and Writing Numbers

In the information society. communication is everything, In order to communicate information, we have to speak the same language and use the same vocabulary.

Let’s Get Started

Our number system in a base -10 place-value system. We use 10 different digits to form all the numbers. The value of the digit depends on which place it is in.

Period – A grouping of three palces in the place-value chart. Each period has a ones place (O), a tens place(T), and a hundreds place (H).

Standard Form – A number written with digits.
124
614,900
70,142, 859

Word form – A number written with words.

One hundred twenty-four
Six hundred fourteen thousand, nine hundred
Seventy million, one hundred forty-two thousand, eight hundred fifty-nine.

Expanded form –  A number written as the sum of its place values.

124 = 100 + 20 + 4
614,900 = 600,000 + 10,000 + 4,000 + 900
70,142, 859 = 70, 000, 000 + 100,000 + 40,000 + 2,000 + 800 + 50 + 9

Sometimes expanded form is written this way to show the place values even more clearly:
614,900 = 6 x 100,000 + 1 x 10,000 + 4 x 1,000 + 9 x 100

about expanded form – it doesn’t come up very often in everyday life. Expanded form helps kids understand the amazing idea of place value and the role of zero as a placeholder.

Now. Let’s practice

Write each number in word form.
1. 3,004                 2. 5,700,054            3. 37,000,416

Write each number in standard form.
4. Seventy-five thousand        5. sixteen million, thirty-four

Write each number in expanded form.
6. 45,700     7. 190, 063            8 5,009,802

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