Fast trick to solve number system Q .The smallest 3 digit prime number is ? As we know the prime number are thoes number which only divide by 1 and itself . First of all 100 is the smallest three digit numbers but a perfact square root that is 10*10. Now lets check 101 so as we know- √101 > 102 and √101 < 112 (Here we take 11 because it is prime number) As we now the previous prime number of 11 are- 2,3,5,7,11 now divide the 101 with these prime numbers and and we find out it is not divisible by any of them it means 101 is a prime number. So smallest 3 digit prime number is 101.