# Brain Teasers

Mind challenges.

## Brain Teaser – Ships

There are 5 ships in a port

## Brain Teaser – A Book

A book has N pages, numbered the usual way, from 1 to N. The total number of digits in the page numbers is 1,095. How many pages does the book have?

## Calculate the velocity of water coming out of a double-entry pipe

If we know the volumetric flow rates of the water going into the two branches, then what would be the velocity of the water coming out?

## New Brain Teaser – What is that number?

There is a number less than 3000 that when divided by 2 leaves a remainder of  1, when divided by 3 leaves a remainder of 2, when divided by 4 leaves a remainder of 3, When divided by 5 leaves a remainder of 4, when divided by 6 leaves a …

## 3 Questions for an Engineer

1. How much does a house weigh? 2. How much weight can a rural two-lane bridge hold? Click to Zoom 3. And finally, would this be covered under the home insurance or the car insurance policy?

## Brain Teaser: Fill in the Blanks

Four words with the letters SNT, in that order, have all their other letters removed. You must use the letters below to fill in the blanks. _ _ S _ N T _ _ _ S _ _ N T S _ N _ _ T S _ _ _ N T Letters to use: A, A, E, E, E, I, I, L, L, Q, S, S, U, U

## Brain Teaser: A Sliding Ladder

A 25 ft ladder (assume it is not an extension ladder) is placed with its foot 7 ft away from a building. If the top of the ladder slips down 4 ft, how many feet will the bottom slide out?

## Brain Teaser – An 8-inch model screw

An 8-inch model screw, tested in a water tunnel at a rotational speed of 22.5 revolutions per second and a velocity of flow of 12 feet per second, yields a measured thrust of 28.5 pounds, a torque of 3.45 pounds and an efficiency of 70 per cent. If the model …