The another name of Before and after number is predecessor and successor respectively.
Before number means predecessor which is 1 less or 1 smaller than the given number.
Or if you subtract 1 from the given number we get predecessor. Example 1 : Predecessor of 38
Subtract 1 from 38 we will get predecessor.
So, predecessor of 38 is 38-1 = 37. Example 2 :
Find the predecessor of 90
Predecessor of 90 is 90-1 = 89 Exaple 3 :
Find the predecessor of 12,000
Predecessor of 12,000 : 12,000 – 1 = 11,999 The natural number of 1 has no predecessor because natural number starts from 1.
After number means successor which 1 more or1 greater than the given number.
Or if you add 1 to the the given number we get successor.
So, successor of 42 is 42 + 1 = 43 Example : 1
Find the successor of 999 .
Add 1 to 99 we will get 99 + 1 = 100
So, successor of 99 is 100 Example 2 :
Find the successor of 489
Add 1 to 489 we will get 489 + 1 = 490
So, successor of 489 is 490 Example 3 :
Find the successor of 18,799
Add 1 to 18,799 we will get 18,799 + 1 = 18,800
So, successor of 18,799 is 18,800 As there are infinite numbers so there is no number exist which does not have any successor number. So in short every natural number has a successor.
So there is no last natural number.
There are some examples for which there is no exact answer.
We can count the number of people in any country.
But we may not able to count the number of stars in the sky or number of hair in our heads. We can count them and add 1 to it and we can easily say that we have counted that much only.
It is now clear that there is no largest number.

Practice Questions on before and After Number

1) Write the next three natural numbers after 20999.
2) Write the two whole numbers occurring just before 80002.
3) Write the after number of : (a) 2,440,501 (b) 1099
4) Write the before number of : (a) 3090 (b) 567,812
5) In each of the following pairs which number is the before number.
(a) 499 ; 498
(b) 120 ; 121
(c) 8967 ; 8966
(d) 12,999 ; 12,998
6) State True or False
(a) All natural number has successor.
(b) The natural number 1 has no predecessor.
(c) The after number 679 is 680.
(d) The whole number 0 has no before number.
(e) The after number of two digit number is always a two digit number.