L2 : Successor & Predecessor - Whole Numbers , Maths, Class 6 Video Lecture

hello friends this video on whole
numbers part 2 is brought to you by exam
feel calm no more fuel from exam now the
moment we talk about numbers have you
observed something that numbers are in
queue they are always in a line one
number after another like how do you
stand when you go to a ticket counter
maybe you won't watch a movie and you go
to the ticket counter to buy a ticket or
maybe you have gone for shopping and now
you are standing in a queue to pay the
bill so how do you stand like one person
after another so you look at any person
there could be one person in front of
them and one person behind him so that's
how the queue is now in a very similar
way numbers are also in queue one number
after another so you consider any number
let's see you can see the three so three
has two before it three has four after
it you think of five five has four
before it and six after it think of six
six has five before it and seven after
it so every number has another number
before it and Onaga number after it so
now the question with regards to number
is who is before and who is after which
number comes before and which number
comes after now this concept of before
and after is given a mathematical term
called a successor and predecessor so
successor and predecessor so the term is
successor for after number that means a
number which is present after the given
number similarly the term used for
before number that is the number which
is present before the specific number is
called predecessor
now the word pre what is pre means pre
means before
so let us understand the concept of
successor and predecessor using this
example where people are standing in a
queue so here if you look at this guy
wearing green t-shirt so this boy is
standing after the one who is in purple
t-shirt so basically for so this green
boy is successor of the purple boy
because the green boy is present after
the purple boy so green is successor of
purple so this is green and this is
purple now what about the green now this
green is present before orange so that
means green is predecessor of orange
because green is present before orange
so any number which is present before a
particular number that number is called
predecessor the number which is present
after the number is called successor so
successor is after number and
predecessor is before number now can you
tell me who is the successor of green
t-shirt looking here looking at this who
would be the successor of green t-shirt
the one who is present after green that
is orange
similarly who would be the predecessor
of the orange t-shirt the predecessor
would be green because green is present
before orange so let us now look at
successor and predecessor of numbers so
let us look at these numbers 1 2 3 4 5 6
7 8 9 and 10
now looking at these numbers you can
very easily say what a successor of five
successor of five would be six successor
of six would be seven successor of seven
would be a successor of line would be
ten so very easily you can say that
looking at the sequence of numbers
similarly you can see that the
predecessor of five is four predecessor
of four is three predecessor of three is
two and so on but what about finding the
successor and predecessor of bigger
numbers let's say if I ask you what is
the successor of 400 so how exactly do
we find successor or predecessor of
numbers because it is not possible for
us to keep writing the entire sequence
of numbers so the simple tip is that
whenever you have to find successor
just add 1 to that number because the
moment you add one you actually go to
this next number so if you add 1 to 4
where do you go 4 plus 1 is 5 so you
actually reach to the next number
similarly whenever you have to find the
predecessor subtract 1 so when you
reduce 1 from a number you go to the
before number so let us consider
examples of bigger numbers let's say 72
so if you have to find out successor and
predecessor of 72 how will you find so
the successor would be 72 plus 1 that is
73 and the predecessor would be 72 minus
1 that is 71 so therefore we can see
that 71 is the predecessor and 72 go in
sub and 73 is the successor let's
consider another example I get bigger
number for example 4 9 6 1 so if you
have to find out the successor and
predecessor of 496 1 so successor would
be 4 9 6 1 plus 1 and predecessor would
be 496 1 minus 1 so 4 9 6 1 plus
would be 496 to and minus 1 would be 4 9
6 0 so in this way we can find out the
successor and predecessor of numbers now
when we actually start looking at the
successors and predecessors of natural
numbers and whole numbers we conclude
certain points for example we conclude
that successors of all natural numbers
are natural numbers so you think of any
natural number their successors will be
natural number because natural number
starts from 1 right so starting from 1
every natural number will have a
successor which is a natural number
because one will infinity all numbers
and natural numbers
similarly successors of all whole
numbers or whole numbers so whole
numbers would start from zero so
successor of 0 is 1 successor of
Cavanaugh's to 2 successor is 3 and so
on similarly when we look at the
predecessor we see that predecessor of
all natural numbers and natural numbers
except 1 why because the predecessor of
1 is 0 and 0 is not a natural number so
1 is the only exception except 1 all
other natural numbers predecessors are
also natural numbers what about
predecessor of whole numbers do you
think predecessor of all whole numbers
would be whole numbers no that's because
when you look at 0 what would be the
predecessor of 0 what exists before 0
now before 0 exists the negative numbers
now about which you will study later in
your higher classes but for now you
should just know that before 0 comes the
negative number so I will give you one
example to prove that why negative
numbers exist before 0 let's say that
you have 10 rupees in your wallet and
you go to the market you buy a pencil
for 2 rupees so how much is left with
you
8
is left with you you again buy another
pencil for two rupees so a you again
lose two rupees so how much is left with
you six rupees now in this way you keep
buying almost five pencils so you spend
the entire ten rupees so what is left
with you
zero you do not have anything but now
let's say you still want to buy a candy
now in order to buy candy you do not
have money now because you have zero in
your wallet so what do you do you go to
the shopkeeper and you tell him that you
give me the candy and you write it in
your you you keep a record of the bill
or you keep the bill with you I will
return the money later so basically what
you did your balance earlier was like
positive balance because you had some
money in your wallet but now you do not
have money in your wallet on top of that
you have taken a loan of two rupees from
the shopkeeper so that means overall
your balance is negative so your balance
is minus - no you do not have money plus
you owe money to somebody else you need
to return money to somebody else so that
that means you went to a negative
balance so that is why we say that
before 0 are the negative numbers and
the negative numbers are not whole
numbers so therefore predecessors of all
whole numbers and not whole numbers the
exception is 0 thank you please visit
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