Page 131 - NUMINO Challenge_C2

15 Clever Solutions

Basic Concepts Clever Problem

At first, difficult problems may seem easy, but they might be tricky. Think
creatively to solve tricky problems easily.

Snail Crawling Up a Well

A snail is crawling up a well that is 10 m deep. Today is
It crawls up 3 m each day but slips down 2 m the 8th day so
each night. You may think that it takes 10 days I start at 7 m.

for the snail to reach the top of the well

because the snail goes up 1 m each day. But

after the 7th night the snail is 3 m from the top of the well, and on the 8th day

it can reach the top.

Empty Bottle Problem
You can trade in three empty bottles for a free bottle of soda. Therefore, if
you buy nine bottles of soda, you can drink 13 bottles of soda.

13 bottles

Example Ben’s mother has seven boys. Her oldest son is named Firsty, her
2nd oldest son is named Secondy, her 3rd oldest son is named
Thirdy, her 4th oldest son is named Forthy, her 5th oldest son is
named Fif thy, and her 6th oldest son is named Sixthy. What is the
name of her 7th oldest son?

Class Notes .

One of Ben’s mother’s sons is named Ben.
Since none of the six sons is named Ben, the name of her 7th oldest son is

Try It Again You can trade in four empty bottles for a free bottle of soda at
the nearby supermarket. If you buy 13 bottles of soda, how
many bottles of soda can you drink?

128 NUMINO Challenge C2