Numbers
Place value
Place value tells us the place of each digit within a number.
The above diagram shows the number 5,892,643. Each of the digits have a
specific place and so they each have a name.
So, the digit 5 has a value of 5,000,000, which is the same as 5 million.
You need to know how to describe whole numbers. For example, 8,000 is
described as ‘eight thousand’ and 158,000 is described as ‘one hundred and
fifty-eight thousand’.
Multiplying by 10, 100 and 1000.
When multiplying a number by 10, all of the digits move to the left by one
place. This means that the units become tens, tens become hundreds and so
on.
So, for example, if we multiply 46 x 10, we will get 460.
A similar method is done when multiplying by 100.
When multiplying a number by 100, instead of moving all of the digits to the
left by one place, you move them all by two places. This means that units
become hundreds and tens become thousands and so on.
So, for example, 32 x 100 = 3200.
,You might have guessed. If we want to multiply by 1000, we move all of the
digits to the left by three places.
For example, 68 x 1000 = 68000.
Dividing by 10, 100, 1000.
When we want to divide a number by 10, we move the digits one place to the
right.
= 36
When we want to divide a number by 100, we move the digits two places to
the right.
= 14
When we want to divide a number by 1000, we move the digits three places to
the right.
= 12
Number lines
A number line is a line that has both positive and negative numbers in order.
The numbers that are above zero are known as positive numbers and the
numbers below zero are known as negative numbers. Negative numbers have
a minus (-) sign in front of them.
Zero is in the middle of the positive and negative numbers. It is neither of
them.
The positive numbers are higher and bigger than the negative numbers. We
can say that 5 is higher than -2.
, Whenever you want to add or subtract numbers, you should always
begin at 0.
When adding a positive number, you count to the right. When subtracting
positive numbers, you count in the left direction.
The example above shows us how to do 2 + 5. We begin on number 2 count
towards the right, 5 times. We land on number 7.
The above example shows us how to do 10 – 6. We begin on 10, and count to
the left 6 times. We land on number 4. This is the answer.
Sometimes, we need to add or subtract many numbers.
Example:
5 – 3 – 1 = 1.
Always draw out a number line.
, Remember this:
Adding positive numbers means count to the right.
Adding negative numbers means count to the left.
Subtracting positive numbers means count to the left.
Subtracting negative numbers means count to the right.
When two signs are next to each other:
When two different signs are next to each other, you should subtract.
When two of the same sings are next to each other, you should add.
Example:
1. 4 - - 2 = 4 + 2 = 6
2. 6 + - 3 = 6 – 3 = 3
Place value
Place value tells us the place of each digit within a number.
The above diagram shows the number 5,892,643. Each of the digits have a
specific place and so they each have a name.
So, the digit 5 has a value of 5,000,000, which is the same as 5 million.
You need to know how to describe whole numbers. For example, 8,000 is
described as ‘eight thousand’ and 158,000 is described as ‘one hundred and
fifty-eight thousand’.
Multiplying by 10, 100 and 1000.
When multiplying a number by 10, all of the digits move to the left by one
place. This means that the units become tens, tens become hundreds and so
on.
So, for example, if we multiply 46 x 10, we will get 460.
A similar method is done when multiplying by 100.
When multiplying a number by 100, instead of moving all of the digits to the
left by one place, you move them all by two places. This means that units
become hundreds and tens become thousands and so on.
So, for example, 32 x 100 = 3200.
,You might have guessed. If we want to multiply by 1000, we move all of the
digits to the left by three places.
For example, 68 x 1000 = 68000.
Dividing by 10, 100, 1000.
When we want to divide a number by 10, we move the digits one place to the
right.
= 36
When we want to divide a number by 100, we move the digits two places to
the right.
= 14
When we want to divide a number by 1000, we move the digits three places to
the right.
= 12
Number lines
A number line is a line that has both positive and negative numbers in order.
The numbers that are above zero are known as positive numbers and the
numbers below zero are known as negative numbers. Negative numbers have
a minus (-) sign in front of them.
Zero is in the middle of the positive and negative numbers. It is neither of
them.
The positive numbers are higher and bigger than the negative numbers. We
can say that 5 is higher than -2.
, Whenever you want to add or subtract numbers, you should always
begin at 0.
When adding a positive number, you count to the right. When subtracting
positive numbers, you count in the left direction.
The example above shows us how to do 2 + 5. We begin on number 2 count
towards the right, 5 times. We land on number 7.
The above example shows us how to do 10 – 6. We begin on 10, and count to
the left 6 times. We land on number 4. This is the answer.
Sometimes, we need to add or subtract many numbers.
Example:
5 – 3 – 1 = 1.
Always draw out a number line.
, Remember this:
Adding positive numbers means count to the right.
Adding negative numbers means count to the left.
Subtracting positive numbers means count to the left.
Subtracting negative numbers means count to the right.
When two signs are next to each other:
When two different signs are next to each other, you should subtract.
When two of the same sings are next to each other, you should add.
Example:
1. 4 - - 2 = 4 + 2 = 6
2. 6 + - 3 = 6 – 3 = 3
