You need to remove four matchsticks from the picture below and still maintain the following:
1. 1st row contains 12 matchsticks
2. 3rd row contains 12 matchsticks
3. 1st column contains 12 matchsticks
4. 3rd column contains 12 matchsticks

It’s hard to give up.
Remove part of it and you still have a bit.
Remove another part, but bit is still there.
Remove another and it remains.
What is it?

Suppose 4 digits 2 ,4,6 and 9 are given.
You have to make a four-digit number.
In how many ways it can be done, if repetition of the numbers does not allowed?