Question 191
Find a 4-digit odd number using each of the digits 1,2, 4 and 5 only once, such that when the first and the last digits are interchanged, it is divisible by 4.
Question 191
Find a 4-digit odd number using each of the digits 1,2, 4 and 5 only once, such that when the first and the last digits are interchanged, it is divisible by 4.
We know that 4- digit number is said to be an odd number, if unit place digit is an odd number (i.e. 1 or 5 )
Given digits are 1,2,4 and 5.
Total such odd numbers are 4125 ,4215 ,1245 ,1425, 2145, 4251, 4521, 5241, 5421, 2451 and 2541.
Also, we know that, any 4-digit number can be divisible by 4, if the last two digits of that number is divisible by 4.
Consider a number 4521.
If we interchange the first and the last digits, then the new number = 1524
Here, we see that the last two digits (i.e. 24), which is divisible by 4.
So, 1524 is divisible by 4.
Required 4-digit number = 4521.
There are three more numbers 2415, 2451 and 4125 which are divisible by 4.
We know that 4- digit number is said to be an odd number, if unit place digit is an odd number (i.e. 1 or 5 )
Given digits are 1,2,4 and 5.
Total such odd numbers are 4125 ,4215 ,1245 ,1425, 2145, 4251, 4521, 5241, 5421, 2451 and 2541.
Also, we know that, any 4-digit number can be divisible by 4, if the last two digits of that number is divisible by 4.
Consider a number 4521.
If we interchange the first and the last digits, then the new number = 1524
Here, we see that the last two digits (i.e. 24), which is divisible by 4.
So, 1524 is divisible by 4.
Required 4-digit number = 4521.
There are three more numbers 2415, 2451 and 4125 which are divisible by 4.
