why number 8549176320 is one of a kind?

What can you hold in your right hand, but never in your left hand?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

Doctor Alex and a bus driver John are both in love with the same woman named Olivia. The bus driver need to go for a long trip of 10 days, Before he left he gave Olivia 10 apples.

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?