0
997.
To test that 997 is prime, we only need to test values up [997^.5], so up to 31. Using divisibility rules, we can immediately eliminate several possible divisors.
Rule for 7: If you have a number, separate the last digit from the proceeding ones. Subtract twice the last digit from the number created from slicing off the last part. if that's divisible by seven, the whole number is. For example, take 343. 34-2(3) is 28, which is divisible by 7, so 343 is divisible by 7
Rule for 3: sum of digits is divisible by 3.
Rule for 2: last digit is divisible by 2.
Rule for 2^n: last n digits form a number that is divisible by 2^n
Rule for 5: last digit is 5 or 0.
Rule for 11: Difference of alternating sums of the digits, 432113 is divisible by 11 because (4+2+1)-(3+1+3) is divisible by eleven.
Rule for 9: sum of digits is divisible by 9.
Trying 13, 17, 19, 23, and 29, we see these all fail. So 997 is indeed prime.
Wiki User
∙ 12y ago
Add your answer:
Earn +20 pts
What is the largest prime number less than 100?
9797 is the largest prime number less than 100.
What is the largest prime number less than 70?
67 will be the largest prime number less than 70.
What is the largest prime number that is less than 100?
9797
What is the largest prime number less than 20?
19
What is the largest prime number less than 40?
37
What is the largest prime no lesser than 1000?
The largest prime number less than 1000 is 997.The largest prime number no less than 1000 is currently 257,885,161-1
How do you find out largest prime number less than 1000?
Start with 1000 and work back, rejecting any composites that you find.
What is the largest prime number less than 100?
9797 is the largest prime number less than 100.
What is the largest prime number less than 70?
67 will be the largest prime number less than 70.
What large prime number less than 50?
The largest prime number less than 50 is 47.
What is the largest prime number less than 37?
The lowest prime number that is less than 37 is 29.
What is the largest number less than 1000?
It is 999.
What is the largest number less than 100 that is relatively prime to 167?
Since 167 is a prime, any number smaller that 167 will be relatively prime. So, the largest number less than 100, that is 99, is relatively prime.
What is the product of the last prime number less than 100?
97 is the largest prime number less than one hundred.
What is the product of the first prime number less than 100?
97 is the largest prime number less than one hundred.
What is the largest number less 1000 that is divisible by 8?
1000 ÷ 8 = 125 → largest less than 1000 divisible by 8 is 124 x 8 = 992
What is largest prime number less than 20?
19
