Transcript Document

Division
by One Digit
Divisors
Allegra James
and Larry Wershbale
Media Design and Production
ISTC 665
What are you doing when
you divide?
• When you divide, you
are trying to split
something into equally
numbered groups
• Dividing these 16 apples
into 4 equal groups,
gives you 4 groups that
have 4 apples in each of
the groups:
• Take these 16 apples:


   
   
Division by One-digit Divisors
• Today you will learn how to divide a
three-digit dividend by a one-digit
divisor, to get a quotient without a
remainder
• Let’s review these terms
What are the parts of a
division problem?
•
•
•
•
The dividend is the number you are dividing
The divisor is the number you are dividing by
The quotient is the evenly divided result
The remainder is what is left over that cannot
be evenly divided
When we write the problem
like this:
136  5 = 27 r 1
136
is the
dividend
5
is the
divisor
27
1
is the
is the
quotient remainder
When writing it like this:
5, the
divisor,
moves
to here
27 r 1
1 is the
remainder
5
136
27, the
136, the quotient,
stays
dividend,
here
moves here
How do you solve a
division problem?
• Solving a division problem is a step by step
process
• The method we will learn today is based the
words for the people in our families.
• They are:
Father
Mother
Sister
Brother
The “Family” Method
Father = Find
Mother = Multiply
Sister = Subtract
Brother = Bring Down
Father
• Father stands for find
• Start by looking at the first number in the dividend
• Find the multiple of the divisor that comes closest
to that number, without going higher
• Use your knowledge of math facts, or a
multiplication grid
Father = find the number closet to the first digit
3
2
711
• In the 3’s, the number
closest to 7, but not
more than 7, is 6
• The other factor is 2
• Put a 2 above the 7
2
6
Mother = multiply the number that is the
factor that you found times the divisor
• You found 2, multiply
it times the divisor, 3
• 2 times 3 equals 6
2X3=6
• Put a 6 under the 7
3
2
711
6
Sister = subtract the number you got by
multiplying the divisor,
from the number in the dividend
• You got a 6 when you multiplied
• Subtract 6 from 7
• 7–6=1
2
3
711
–6
1
• The difference must be smaller than the divisor!!!
Brother = bring down the next number,
from the number in the dividend
• Bring down the next number in
the dividend
• The new number you have is 11
2
1
3
711
–6
11
• Now start over again with Father for the ten’s
Now, let’s do the second step
• Father: 9 is the closest multiple,
the other factor you found is 3
• Mother: 3 X 3 = 9, put a 9 under
the 11
• Sister: subtract 9 from 11
11- 9 = 2
• Brother: bring down the 1
23
1
3
711
–6
11
–9
21
Now, let’s do the last step
•
•
•
•
2 37
Father: 21 is the closest
1
3
711
multiple, the other factor is 7
–6
Mother: 7 X 3 = 21, put 21 under
11
the 21
–9
Sister: subtract 21 from 21
21
21- 21 = 0
–
21
Brother: nothing’s left, you’re done!
0
Now, let’s practice!
• Father
• Mother
• Sister
• Brother
2
6
864
4
8
–8
06
Now, let’s do the second step
• Father
• Mother
• Sister
• Brother
21
64
4
864
–8
06
–4
24
Now, let’s do the last step
• Father
• Mother
• Sister
• Brother
2 16
6
4
864
–8
06
–4
24
– 24
0
What do I do with division now?
• Finish the rest of the worksheet
• Homework: probs. 1-10, p. 64 in text
• Go to this icon
on the class’
computers for extra practice if you have
free time
• Look for the same icon on the class’
website for practice at home