How is the moon similar to a dollar?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

What does this mean?

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The husband and wife were jogging in the morning. To match every two steps of the husband, the wife required three steps. If Both of them start with the here right foot. After how many steps do their left foot be together?

You have three orange, two pink and five purple balls in the drawer beside your bed. There is no electricity and the room is entirely dark. How many balls must you take out to ensure at least one ball of each colour at least?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

Find the next number in the series below

21 32 54 87 131 ?

Spot what is wrong here in below Picture?

Which part of London exists in France as well ?