powerfree numbers..

new inventions in number theory .. [summary]

1. a number is not a power of 6 if it’s last two digits are not one of these: 16, 36, 56, 76 or 96, always … OR integer whose 2nd digit to left from right is any odd numbers less than 10 (1,3,5,7..etc)

2. a number is not a power of 5 if it’s last two digits are not 25

3. for powers of 4, always either a 4 or a 6 in the last digit (which adds upto 10)

4. powers of 7: last digit is always an odd number less than 10 but not 5.

5. for powers of 3 is same as that of 7 but their 2nd last digit differ..