What’s the number?

It’s not easy having a mathematics professor as a new friend. When she invites you to her house she says, “All the houses on my side of the street are numbered consecutively in even numbers. There are six houses on my side of my block and the sum of their numbers is 9870. You don’t know which block I live on, and it’s a long, long street, but I will tell you that I live in the lowest number on my side of the block. What’s the number? Or are you just going to ring the first even-numbered doorbell for twenty blocks?

Click here for the solution

She lives at number 1640.

more riddles

How old is Mike?

David and Mike are brothers. David is 33 years old today. This is three times as old as Mike was when David was the age that Mike is today.How old is Mike?Mike is 22 years old.more riddlesDonec rutrum congue leo eget...

read more

How many balls?

Glenn and Jason each have a collection of cricket balls. Glenn said that if Jason would give him 4 of his balls they would have an equal number; but, if Glenn would give Jason 4 of his balls, Jason would have 3 times as many balls as Glenn.How many balls does Jason...

read more

How can this be?

A certain large animal lives happily and thrives here on Earth. One day, every single one of these critters is wiped out by a mysterious disease which affects only this particular animal. There are none left anywhere on earth -- they are all gone. About a year or so...

read more

Which ball?

Two barrels contain each the same amount of water. The water temperature in one barrel is 49°F while the other is at 29°F. Two golf balls of same dimension and weight are dropped simultaneously into the barrels. The golf balls are dropped from the same height.Which...

read more