Numbers
Girls Engaged in Math and Science
June 2012
How many is this?
What are some different ways we can write
that?
• 10
•||||||||||
• 2x5 (this works, but there are LOTS of things that
equal ten)
what is this?
•ten
ten
• others?
• X (Roman Numeral)
•||||
||||
THE WORD “TEN”
• What are written words made of?
• How many letters are there in the
English alphabet?
• How many words can you make of
them? Just a guess?
What is this way of writing numbers made of?
10
Numerals
• How many numerals are there?
• Starting from zero, what are the
numerals?
0 1 2 3
4
5
6
7
8
•
9
How many numbers can you make out
of these numerals?
•
How come we have ten numerals?
•
Is it because we have ten fingers?
Aliens!!!
What if we were
aliens with only two
fingers??
How many
numerals
would we
have?
2 Numerals
• How many numbers could we write out
of 2 numerals?
• What is the problem with this?
Could a person or
alien with two
fingers do this?
No, but....
• How do you represent 55 with your
fingers?
• Let’s see how we could do the same
0
0
•
type of thing with only two digits.
11 2
3
4
5
6
7
8
9
• Okay!! Let’s start counting with two
numerals!!
0
1
Is that it?
Poor aliens!
• Wait! What do we do on this planet
when we run out of numerals at 9?
• 10
• Why?
• You have put more than one numeral
here and you’ve already used these
numerals, how can you use them
again?
• What column do you put the 1 in?
• Why is it called that?
What does this 1 and 0 mean when
written in different columns?
What is the next number that needs a new column?
one ten
no ones
Is the “tens column”
called the tens column
because TEN is the first
number that needed a
new column for you to
be able to write it?
• What do you have to change to get from
nineteen to twenty?
one ten
two tens no ones
nine ones
The aliens are back!
• If we go back to the two
digit counting, we have:
0
1
10
we ran out
of digits so
we need a
new column.
TWO’s Column
this is NOT
ten in the
alien world,
it’s two!
one two zero ones
this is NOT
eleven in
the alien
world, it’s
____?
one two one one
Even though 10
meaning two seems
funny to you, it’s
because from the time
you were a little baby,
10you were taught that it
means
is called ten, not two.
two!!
Alien children are taught
that 10 is two. You can
get used to it, alien
children do!
0
zero
1
one
11
three
1000
1000
eight
110
six
111
twelve
101
five
1010
ten
1001
seven
1100
100
100
four
10
10
two
1011
nine
eleven
1101
1110
thirteen
fourteen
So, NOW how many numbers
can you write with two
numerals?
• So, who uses this stuff?
If you were
going to give What’s this?
each position a
number instead
How
many
of writing “on”
positions
and “off” what
does it
numbers would
have?
you use?