In post 138, word321 wrote:6. What is the last digit of 7^49?
It should be 7.
Proof:
=mod(7^1,10) = 7
=mod(7^2,10) = 9
3
1
repeat (7,9,3,1)
In post 138, word321 wrote:6. What is the last digit of 7^49?
4. Prove that a number is a multiple of 2 if the last digit is a multiple of 2, and that a number is multiple of 5 if the last digit is 0 or 5.
Prove that a number is multiple of 3 if the sum of its digits is a multiple of 3
In post 154, implosion wrote:I suspect it's 1/2 but am not confident and am intrigued to try to show it formally and will think about it more later
In post 163, mith wrote:How I've been keeping busy during a pandemic...