



When we write "one dollar"
we sometimes write: 





$1.00



That is because our money is divided
up 


into pieces of dollars called cents. 





The number on the right of
the period 


(in math we call it a decimal point) 


are for those pieces
of a dollar. 





To write a quarter (also known as 25 cents), we can
write: 





$0.25






Two quarters
(sometimes known as 50 cents but never 50 cent) 


looks like this: 





$0.50 





The "S" with a line through
it is just a code. 


This
code says we're talking about dollars or pieces of dollars. 


It's not really part of the number. 





We could
use addition and add two quarters 


to get 50 cents like this: 











If we start with two quarters (fifty
cents) 


and add another two quarters (fifty cents), 


it looks like this: 











No big
surprise here. 


Most people know that 4
quarters is the same as a dollar. 


The
big thing is to see how these numbers add
together. 





WHEN
YOU ADD THESE NUMBERS, 


THE DECIMAL POINTS MUST LINE UP. 





Example: 





Add
38 cents plus 24 cents: 











We
can do subtraction with this stuff too! 





Example: 





81
cents minus 30 cents: 











The
word cent comes from some foreign language. 


It
means 100. 


There
are 100 cents in a dollar. 


This
is like a pizza with 100 slices. 


Each
cent is one slice. 





In
our "slice of pizza" way of writing numbers, 


we
could write one cent like this: 











Using
our new decimal point way, we can write one cent like this: 





$0.01 





But
hey! A penny is a penny no matter how you write it so: 











There
are 4 quarters in one dollar. 


Using
the "pizza slice" fraction method, 


we
can say that there are 4 quarter sized slices in one dollar. 


So
for ONE quarter we can write: 











Using
our new decimal point method 


we
can write one quarter (25 cents) as: 





$0.25



And
a quarter is a quarter so: 











Example:






There
are 10 dimes in a dollar (like a pizza with 10 slices) 


each
dime is also worth 10 cents. 


If
we wanted to add two dimes together we could write: 











And
we could also write: 











copyright 2005 Bruce Kirkpatrick 
