Introduction
In the chapter,
Unit, Number, Numeral and Number System,
we learnt how to write counts of a thing using units and numerals. Let’s take it to the next step, but how much
a thing, in other words, is it more or less in numbers.
So how do we compare numbers if one is bigger than the other. Here, comes the concept of Face value and
Place value, that helps in understanding the number system in mathematics.
Eventually, it clearly helps to know which is cheaper, a watch with a price tag of $20 or $200.
This is not the end, we do numerous mathematical operations on numbers for example addition, subtraction,
multiplication and division on numbers.
The process involved in handling these arithmetic operations are based on understanding of these basic concepts
of place value.
To write any number bigger or shorter we use digits. There are 10 digits in the number system which helps
us to
write any number in mathematics. When we use ten symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 to represent any
numbers,
these ten symbols are called Digits or Figures.
In the above example, which is cheaper, a watch with a price tag of $20 or $200, to compare the two numbers 20
and 200 we should learn before all how the numbers are written using place value and face value.
In the next step, let’s learn face value and place value by seeing examples.
What is face value in maths?
The Face Value of a digit in a number is equal to the same digit itself and it is also known as true value. The face value of a digit is always equal to the digit itself.
Consider a number 34872
Face value of 3 in number 34872 is 3.
Face value of 4 in number 34872 is 4.
Face value of 8 in number 34872 is 8.
Face value of 7 in number 34872 is 7.
Face value of 2 in number 34872 is 2.
What is place value in maths?
Place Value is a value of digit in a number and it is also known as local value. For example, the place
value of digit 2 in number 34872 is 2, the place value of 7 is 70 and place value of 8 is 800.
You can notice as we move from left to right in 34872 we add that much number of zeros behind the digits.
How?
To find the place value of a digit in a number, we always move from right to left. The first position on the
right is called 1s, and read as ones. The second position is 10s and read as tens. The next positions go as 100s
and 1000s and so on.
Let’s start moving from left to right in number 34872. As we move, we keep on increasing the number of zeros by
one behind the digits.
So, no zero behind 2. One zero behind 7, Two zeros behind 8. Three zeros behind 4. Four zeros behind 3.
Or we can write it as multiply the digits with 1s, 10s, 100s, 1000s and 10000s depending upon their position:
2 is at 1s place, so 2 × 1 = 2
7 is at 10s place, so 7 × 10 = 70
8 is at 100s place, so 8 × 100 = 800
4 is at 1000s place, so 4 × 1000 = 4000
3 is at 10000s place, so 3 × 10000 = 30000
So, we get the place value of each digit in 34872 as 2 of 2 , 70 of 7, 800 of 8, 4000 of 4 and 30000 of 3.
In general we can find the place value of a digit at a position by multiplying the face value by the value of
place.
Place Value = Face Value X Value of Place
Place Value of 4 in number 34872 is calculated as:
4 × 1000 = 4000, where face value = 4 and value of place = 1000
Place value of repeating digits
If a digit appears more than one time in a number, the place value of that number will be different and depends upon its position in the number. Let’s understand it with an example.
Consider a number 348742, 4 repeats two times at 10s and 10000s place.
Place value of 4 at 10s place = 4 × 10s = 40.
Place value of 4 at 10000s place = 4 × 10000s = 40000.
Therefore, we can see the repeating digit 4 has two different place values 40 and 40000 in the same number
348742.
Compare two numbers
Place value helps us in comparing two or more numbers to check which is the greatest number or which is the smallest number.
1. Compare two numbers with unequal number of digits
In general, we are aware that the number which has more digits than the other number is greater than the other number. This is a good thumb rule to compare two numbers which have different numbers of digits.
Two watches with a price tag of $20 or $200 have different numbers of digits.
20 has two digits 2 and 0. 200 has three digits 2, 0 and 0. So, 200 is greater than 20 because 200 has more
digits than 20 and that makes a $200 watch costlier than a $20 watch.
2. Compare two numbers with equal number of digits
Above we learnt how to compare two numbers with unequal numbers of digits. The same is not the case when the
number of digits in two numbers are equal.
We check such numbers using the place value of the left most number. If the leftmost number’s place value is
greater than the other then the number is greater also than the other number.
Consider two numbers with equal numbers of digits, i.e. 3, as 246 and 514.
Step1: Take the leftmost digit of 246 which is 2.
Step2: Find the place value of 2, which is 2 × 100s = 200
Step2: Take the leftmost digit of 514 which is 5.
Step3: Find the place value of 5, which is 5 × 100s = 500
Step4: Compare 200 and 500, which is greater? It is 500.
Step5: That means 514 is greater than 246.
In the above example of two numbers 246 and 514, the leftmost digits are different i.e. 2 and 5. There can be a task to compare two numbers with equal numbers of digits and where the leftmost digits are the same.
Consider two numbers 246 and 214 which have equal number of digits i.e. 3 and have the same leftmost digit
i.e. 2 in both numbers.
If we follow the above steps to compare them then both have 200 place value for the leftmost digit 2,
because 2 is at 100s place and 2 × 100 = 200.
In such numbers where the leftmost digit is the same, we move to the next right number and see which is
greater using the above method.
Here, 4 is the next right number in 246 and 1 is the next right number in 214. Both 4 and 1 are in 10th
place.
So, the place value of 4 in 246 is 4 × 1 = 40 and place value of 1 in 514 is 1 × 10 = 10.
So, 40 is greater than 10. That means 246 is greater than 214.
