Transcript Lesson 2-4a

2-4
6th grade math
Dividing by Whole Numbers
Objective
• To divide whole numbers and decimals by
whole divisors
• Why? To be competent in solving number
sense problems involving whole numbers and
decimals.
California State Standards
NS 2.2 (Gr. 5): Demonstrate proficiency with
division, including divisions with positive
decimals and long division with multi-digit
divisors.
AF 1.2: Write and evaluate an algebraic expression
for a given situation, using up to three variables
MR 2.7: Make precise calculations and check the
validity of the results from the context of the
problem
How to Solve Dividing a Whole
Number by a Whole Number
1)Use an estimate to help you
place the first digit in the
quotient
2) Line up your numbers in
the quotient and the work
underneath
3) Subtract
4) If there are still more
number to divide, pull
down the next number to
the previous remainder.
Until you get 0 as a
remainder.
114
23 2,622
-23↓↓
32↓
-23↓
92
-92
0
How to Solve Dividing a Decimal by a
Whole Number
*
1) Place a decimal point in
the quotient directly
over the decimal point
in the dividend
2) Divide as with whole
numbers. Use your
estimate to help you
place the first digit
3) Place your digits and
subtract carefully.
Remember your
placeholders.
$5.26
5 $26.30
-25 ↓ ↓
13↓
-10 ↓
30
-30
0
How to Solve Dividing and Needing
to Add 0’s in Dividend
1) If a decimal is in the
dividend, place a
decimal point in the
quotient. Then divide. If
a decimal is already in
place, skip Step 1.
2) Place a 0 in the tenths
place. Then divide.
3) Place a 0 in the
hundredths place. Then
divide. Remember your
placeholders.
*
48. 6
5 243. 0
-20↓ ↓
43
-40 ↓
3 0
-3 0
0
When the Quotient is Less Than 1
1) Place a decimal in
the quotient over
the decimal in the
dividend
2) Place a 0 in the ones
place
3) Divide and follow
the division rules.
Remember your
placeholders.
0. 85
9 7.65
-7 2↓
45
-45
0
0 .032
6 0.192
- 0 18 ↓
1 2
-1 2
0
Since 1 < 6, put a
zero in the tenths
place of the
quotient as a
placeholder.
Try It!
1)
035
13 455
-39↓
1)
13 455
65
- 65
0
0 018
2)
65 1,170
2) 65 1,170
-65↓
520
- 520
0
Try Some More!
3)
0103
38 3,914
3)
-38↓↓
11 4
-114
0
38 3,914
4)
4)
10 4,020
0402
10 4,020
- 4 0↓↓
020
-20
0
And…
5)
5) 22.05 ÷ 70
6) 18.24 ÷ 3
6)
00.315
70 22.05 0
-21 0↓↓
105
- 7 0↓
350
-350 = 0
06. 08
3 18.24
-18 ↓↓
024
-24
0
Yet More …
7)
02.70
12 32.40
-24↓↓
8 4
-84↓
00
7) $32.40 ÷ 12
8) 211.4 ÷ 7
8)
030.2
7 211.4
-21↓ ↓
01 4
-14
0
Is the quotient correct. Check
with multiplication.
9) 2.7 ÷ 9 = 0.3
10) 41.4 ÷ 6 = 6.8
11) 6.03 ÷ 9 = 0/67
9) Correct
10) Incorrect (40.8)
11) correct
Objective Review
• To divide whole
numbers and decimals
by whole divisors
Why? You are now competent
in solving number sense
problems involving whole
numbers and decimals.
Independent Practice
• Complete problems 1324
• Complete problems 2535
• Copy original problem
first.
• Show all work!
• If time, complete Mixed
Review: 36-50
• If still more time, work
on Accelerated Math.