in base 5 devise test for:
divisibility by 2,4,5
Hello, teeplkyl!
In base-5, devise tests for divisibility by 2, 4, 5
Divisible by 2
If there is an even number of odd digits, the number is divisible by 2.
Examples: .$\displaystyle 2143_5$ is even (298). . $\displaystyle 4032_5$ is odd (517)
Divisible by 4
Add the digits.
If the sum is divisible by 4, the number is divisible by 4.
Example: .$\displaystyle 12,032_5\quad\Rightarrow\quad 1+2+0+3+2 \:=\:8$
. . . . . . . .Since 8 is divisible by 4, $\displaystyle 12,032_5$ is divisible by 4 (872).
Divisible by 5
A number is divisible by 5 if it ends in zero (0).
It is very difficult to study Number Theory topic. Not many good reference textbooks to study Number Theory.
I use A Friendly Introduction to Number Theory, 3rd Edition to study. This is good reference textbook.
Do you have any other good Number Theory related textbooks recommend?
Regards,
Andy