# key stage 2 numeracy -

# Number Place Value

## Place Value

The numerical system that we use today is the Hindu-Arabic system and it is based on the concept of place value. Each numeral's value is dependant on its place. For instance look at the numeral 1 below.

1 = 1 unit

10 = one ten

100 = one hundred

We can express any number using only the digits 0-9. The right hand digit is the number of units, the next left the number of tens, the next left the number of hundreds and so on. In our numbering system the numeral zero has particular importance as it is used as a "place-holder". For instance the number 104 needs the zero to "hold" the tens place. If it was not present we would have the number 14, which is quite different.

It is also important to understand that ten units are equal to one ten and ten tens are equal to one hundred etc., and below we show a method of teaching this to a child.

## Explaining place value to young children

One particularly effective way of teaching place value is through the use of (base-ten) blocks. They visually demonstrate how we can exchange ten units for one ten and ten tens for one hundred etc.

We can put ten units together and physically make a "ten". We can then put ten of the "ten" strips together to make a hundred. Of course we can use 1p, 10p, and £1 coins instead. However they do rely on being able to understand that the one pound coin is equal to ten 10p coins and to one hundred 1p coins, and so it is not quite so clear.

Representing numbers with blocks can then be used to teach addition and subtraction.