After adding + or - before the number 123456, are their algebra and s odd or even? Why? Add a sign between 1, 2, 3, 4, 5, 6, 7, 8, 9

After adding + or - before the number 123456, are their algebra and s odd or even? Why? Add a sign between 1, 2, 3, 4, 5, 6, 7, 8, 9

Take two terms as a whole. For example, 1 and 2.1 + 2,1-2,
-1 + 2, - 1-2. Are all odd numbers. That is to say, five odd numbers are added together. So the answer is odd

How many cards should be drawn from one to five digital cards to ensure that there are both odd and even numbers in the drawn cards

4

There are ten digital cards with 0 ~ 9 written on them. You need to pull out at least () of them to ensure that the two cards are odd or even
1、2 2、3 3、6
The teacher didn't understand what he said in class_

There are five odd and even numbers
If you draw out two pieces of bad luck, the worst is an odd number and an even number. If you draw another piece, you will get two pieces of odd or even numbers
So take three