Explaining ‘numbers’ to children.

 Our number system is worked in BASE 10 and each number has a place value. This means that its value depends on its position.  

In arithmetic the positions are given names

 e.g. 965

When you move from one column to the next starting with the units each number becomes 10 times larger.

In the number 9 6 5
U=5 units
T=6 groups of 10 = 60
H=9 groups of 100 = 900

In these examples the figures underlined have the following values:

3789 3 = 3000 (three thousand)

40327 40 = 40000 (forty thousand)

65891 8 = 800 (eight hundred)

Number Groups

1. Even numbers

 An even number is a number which can be exactly divided by 2

e.g 2 4 6 8 10

2. Odd numbers

 All other numbers are odd

e.g 1 3 5 7 9 11

3.  Prime numbers

A prime number is a number which can only be divided exactly by itself and by one. All prime numbers are odd numbers apart from 2.

1 is not a prime number

5 7 9 11 13 29 53 are some examples of prime numbers

4. Square numbers

These are numbers whose dots can be arranged in the shape of a square

Following from this any number multiplied by itself will form a square

e.g. 16 25 36 etc

The square of a number is written as 7² i.e. 7x7---seven rows and 7 columns equals 49

With a square number the number of dots in each row, or each column is known as the Square root of a number

√ this is the sign for square root √ 25 is 5

5. Rectangular Numbers

These are numbers whose dots can be arranged in the shape of a rectangle.

6. Triangular numbers

 These are numbers whose dots can be arranged in the shape of a triangle

Some numbers are both square and rectangular 16=4x4(square) 8x2=16 (rectangular)

36 is the lowest number which is a square, rectangular and triangular number

Have fun with Numbers