Download Dividing Decimals by Whole Numbers

Dividing Decimals by Whole
Numbers
In long division, we use both
multiplication and division.
Remember our key
Vocabulary…
Parts of a division problem…
GOES
INTO
quotient
divisor ) dividend
DIVIDED
BY
Parts of a division problem…
dividend
divisor
= quotient
dividend ÷ divisor = quotient
Parts of a multiplication problem…
factor x factor = product
To keep your long division steps in order,
remember the basic family…
• DAD
– Divide the divisor into the dividend
• MOM
– Multiply the divisor by the factor you are about
to put into your quotient
• SISTER
– Subtract the product from the
dividend/difference
• BROTHER
– Bring down the next digit in your problem
• ROVER
– Repeat!
Different Ways to Present the Same Problem
36 divided by 9
“Divided by” means
that the first number
is the dividend and
the second number is
the divisor.
9 ) 36
“Divided into” means
that the first number
is the divisor and the
second number is the
dividend.
36 ÷ 9
9 divided into 36
36
9
Writing the Division Problem…
When you are thinking about lunch… I mean long
division… think of In-and-Out.
Setting up your long division problem…
IN – n- OUT
24 ÷ 9
9 ) 24
OUT
IN
Does 9 go
into 24?
Yes. 2 times.
Put the 2 over
the 4 (my last
underlined
number)
2
9 ) 24
-18
6
9 x 2 = 18
Subtract
24-18
2
9 ) 24.0
Bring the decimal
point up into your
answer.
-18
60
Going forward, we will not leave remainders when we
divide anymore. Now you need to add a decimal point to
the end of the dividend and add a zero.
26
9 x 6 = 54
9 ) 24.0
-18
Does 9 go
into 60?
How many
times?
60
-54
6
9 x 6 = 54
60 – 54 = 6
2 66
9 ) 24.00
-18
Repeat the
same steps…
60
-54
60
-54
6
2 66
9 ) 24.00
-18
Do you see
this repeating
pattern?
60
-54
60
-54
6
I see that if I go
one more place,
I will add another
6 to my quotient.
2 6 6 66666
9 ) 24.00
I can see that the six will keep repeating
itself. I am, therefore, going to round my
answer to the hundredths place…
2.666 = 2.67
How do I know where to round my answer to?
• If you are doing a problem from the book or on a
test then read the directions for the answer to
that question.
• If you are in a grocery store trying to figure out
something that will cost money, round to the
pennies place. (hundredths)
• If you see “round to the nearest whole number”
or “round to the nearest dollar,” then round to
the ones place.
• If your answer stops in the thousandths place,
do not round your answer. Leave it as it is!
What do I do if I have zeroes
in my problem?
2
Does 7 go
into 14?
Yes. 2 times.
Put the 2
over the 4
(my last
underlined
number)
7 x 2 = 14
7 ) 1402.52
-14
0
Subtract
14-14= 0
20
Does 7 go
into 0 or
00?
No. Put the 0
in the quotient
over the 0 in
the dividend.
7x0=0
7 ) 1402.52
-14
00
0
0
Bring
down the
zero
0–0=0
20 0
7x0=0
7 ) 1402.52
No. Put the 0
in the quotient
over the 2.
Does 7 go
into 2?
-14
00
0
02
0
2
Bring
down the 2
2–0=2
200
7 ) 1402.52
-14
00
0
02
0
2
Send up
the
decimal
point.
200 3
7 ) 1402.52
-14
Yes. 7 x 3 = 21.
00
Put the 3 in the
0
quotient over the
5.
02
0
25
Does 7 go
21
into 25?
4
7 x 3 = 21
Bring
down the 5
25 – 21 = 4
200 3 6
7 ) 1402.52
-14
Yes. 7 x 6 = 42.
00
Put the 6 in the
0
quotient over the
2.
02
0
25
21
Does 7 go
into 42?
42
42
0
7 x 6 = 42
Bring
down the 2
42 – 42 = 0
And the answer is…
200 3 6
7 ) 1402.52
Let’s Practice…
4.302
3 ) 12.906
103.6
5 ) 518
18.09
6 ) 108.54
151.08
11 ) 1661.88
62.301
22 ) 1370.622