1. what is the largest 2 digit prime number
Solution:
largest 2 digit number is 99
previous prime before 99
We need to test each number to find the previous prime
99 is not prime, because it is divisible by 3
98 is not prime, because it is divisible by 2
97 is prime, So Prime:1 = 97
Previous prime before 99
97
So, 97 is the largest 2 digit prime number.
2. what is the largest 3 digit prime number
Solution:
largest 3 digit number is 999
previous prime before 999
We need to test each number to find the previous prime
999 is not prime, because it is divisible by 3
998 is not prime, because it is divisible by 2
997 is prime, So Prime:1 = 997
Previous prime before 999
997
So, 997 is the largest 3 digit prime number.
3. what is the largest 4 digit prime number
Solution:
largest 4 digit number is 9999
previous prime before 9999
We need to test each number to find the previous prime
9999 is not prime, because it is divisible by 3
9998 is not prime, because it is divisible by 2
9997 is not prime, because it is divisible by 13
9996 is not prime, because it is divisible by 2
9995 is not prime, because it is divisible by 5
9994 is not prime, because it is divisible by 2
9993 is not prime, because it is divisible by 3
9992 is not prime, because it is divisible by 2
9991 is not prime, because it is divisible by 97
9990 is not prime, because it is divisible by 2
9989 is not prime, because it is divisible by 7
9988 is not prime, because it is divisible by 2
9987 is not prime, because it is divisible by 3
9986 is not prime, because it is divisible by 2
9985 is not prime, because it is divisible by 5
9984 is not prime, because it is divisible by 2
9983 is not prime, because it is divisible by 67
9982 is not prime, because it is divisible by 2
9981 is not prime, because it is divisible by 3
9980 is not prime, because it is divisible by 2
9979 is not prime, because it is divisible by 17
9978 is not prime, because it is divisible by 2
9977 is not prime, because it is divisible by 11
9976 is not prime, because it is divisible by 2
9975 is not prime, because it is divisible by 3
9974 is not prime, because it is divisible by 2
9973 is prime, So Prime:1 = 9973
Previous prime before 9999
9973
So, 9973 is the largest 4 digit prime number.
This material is intended as a summary. Use your textbook for detail explanation.
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