When it's bad luck to meet a black cat?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

What is both possible and impossible at the same time?

There were two grandmothers and their two granddaughters.
There were two husbands and their two wives.
There were two fathers and their two daughters.
There were two mothers and their two sons.
There were two maidens and their two mothers.
There were two sisters and their two brothers.
Yet there are only six, who are buried here,
All are born legitimate and relationships clear.
How can this happen?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

Two friends decide to get together; so they start riding bikes towards each other. They plan to meet halfway. Each is riding at 6 MPH. They live 36 miles apart. One of them has a pet carrier pigeon and it starts flying the instant the friends start traveling. The pigeon flies back and forth at 18 MPH between the 2 friends until the friends meet.

How many miles does the pigeon travel?

Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

What is next number in the pattern below:

131 517 192 123 ?

The first person saw the bridge step on it and crossed,
the second person saw the bridge did not step on it but crossed,
the third person did not see the bridge did not step on it but crossed.
Who are these people?

what does this picture(rebus) riddle means ?