



A
dollar just happens to be cut into 100 slices. 


What
if it wasn't? 





There
is nothing so special about a number 


with
2 places on the right side of the decimal point. 


If
our a dollar was cut up into 1000 pieces, 


we
would need 3 number places 


(called
decimal places in fancy math talk) 


on
the right side: 





$1.000






We
could still add this stuff up the same way. 


Just
remember that the decimal point on all numbers MUST line up: 





Examples: 





Add
.391 and .608 ... 











Subtract
.206 from .978 ... 











In
fact, we could have any number of places 


on
the right of the decimal point:






Examples: 











What
happens if we have 2 numbers to add that look like this: 





.3157
+ .23






First,
we line up the decimal points: 











WAIT
A MINUTE! 


There
are 4 digits in the first number and only 2 in the second one! 





So? 





Don't
all the numbers have to have the same number of places 


on
the right side of the decimal point? 





NO!
They do not! 


If
it makes you feel better, you can put in zeros after the .23 


until
it has as many digits as the other number. 


The
zeros won't change the value at all. 





Now
lets add: 











Subtraction
works the same way: 





Example: 





.83
 .011






Step
1: 











Step
2: 











Step
3: 











OK,
Now look at this one ... 





Example: 











How
do we deal with this puppy? 





Remember
the elevator? 


This
time, each floor is .1 instead of 1. 











Did
you notice that the decimal didn't really change the steps at all? 











copyright 2005 Bruce Kirkpatrick 
