Is 43 a Prime Number?
2026-02-28 23:38 Diff
https://brightchamps.com/en-us/math/numbers/is-43-a-prime-number

In the divisibility method, we have to check 43 with different numbers whether 43 is divisible by those numbers or not. The rule is, if 43 is divisible by any number that falls between 2 and the square root of 43 itself, it is composite, or else it is prime. 


Testing the same in case of 43:


Step 1: Checking divisibility by 2


Any even number is divisible by 2. 43 is not an even number, so it is not divisible by 2.


Step 2: Checking divisibility by 3.


Any number is divisible by 3 if the sum of the digits is divisible by 3. 


4+3=7, which is not divisible by 3, so, 43 is also not divisible by 3.


Step 3: Checking divisibility by 4.


Any number is divisible by 4 if its last two digits are divisible by 4. 43’s last two digits are 43 itself, and it is not divisible by 4.


Step 4: Checking divisibility by 5.


Any number is divisible by 5 if its last digit is either 0 or 5. 43’s last digit is 3, hence, 43 is not divisible by 5.


Step 5: Check divisibility by 6.


Any number is divisible by 6, if and only if it is divisible by 2 and 3 both. 
43 is neither divisible by 2 nor by 3, as we checked above.


Also, the square root of 43 is less than 7, so no need to check divisibility greater than 6.

We can conclude that 43 is a prime number and 43 is not divisible by numbers other than 1 and 43.