today our topic of discussion will be: division by 2 digit divisors
Post on 01-Jan-2016
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CONFIDENTIAL 1
Today our topic of discussion will be: Division by 2 digit divisors
Good Afternoon!
Let’s Warm up:.
1) Estimate: 326 ÷ 6
2) 2500 ÷ 5
3) 67 ÷ 7
4) 86 ÷ 9
5) 345 ÷ 4
1) 55
2) 500
3) Q = 9, R = 4
4) Q = 9, R = 5
5) Q = 86, R = 1
CONFIDENTIAL 2
We can apply the concept of Place value to find the solution of multiples of 10.
42 ones ÷ 6 = 7 ones
42 tens ÷ 6 = 7 tens
42 hundreds ÷ 6 = 7 hundreds
42 ÷ 6 = 7
420 ÷ 6 = 70
4,200 ÷ 6 = 700
42 is the Dividend, 6 is the divisor, 7
is the quotient.
REVIEW
CONFIDENTIAL 3
Numbers that are close to the number in a problem and are easy to divide mentally are Compatible Numbers.
The objective of finding Compatible numbers is the Estimation of Quotients.
Compatible numbers help to find the multiple that is closest to the dividend, so it is easier to divide mentally.
Estimate 123 ÷ 4
120 ÷ 4 = 30
120 and 4 are compatible numbers.
REVIEW
CONFIDENTIAL 4
Divide 114 by 3.
STEP 1:
We will solve this with the help of paper-pencil.
3 114
3
-9
2
3 tens in each
group.
2 tens left
11 tens, 4 ones
9 tens used
STEP 2:
3 114
3
-9
24
Bring down 4 ones.
24 ones in all.
REVIEW
CONFIDENTIAL 6
Divide 411 by 4.
STEP 1:
4 411
Estimate to place the first digit.
STEP 2:
4 411
1Divide the hundreds.
4 = 4, enough to divide. So, the first digit is in the hundreds place.
Divide 4 ÷ 4 = 1. Put 1 in the quotient. Subtract 4 – 4 = 0.Place a ‘0’ in the hundredth column.
- 4
0
Quotients with zero.REVIEW
CONFIDENTIAL 7
STEP 3:
4 411
10
- 4
01
Bring down the tens.
Divide the tens.
- 01
1 < 4, not enough to divide. Put 0 in the quotient.Subtract: 1 – 0 = 1
STEP 4: Bring down the ones. Divide the
ones.4 411
102
- 4
01- 011- 8
3
8 < 11, enough to divide. Multiply 4 x 2 = 8. Subtract: 11 – 8 = 3.Compare: 3 < 4, so, 3 is the remainder.
REVIEW
CONFIDENTIAL 8
Let’s start with the new topic now
Find 4,200 ÷ 60
Here also we can apply the concept of Place value to find the solution as in the previous lesson.
42 ones ÷ 6 = 7 ones
42 tens ÷ 6 tens = 7 ones
42 hundreds ÷ 6tens = 7 tens
42 ÷ 6 = 7
420 ÷ 60 = 7
4,200 ÷ 60 = 70
42 is the Dividend, 6 is the divisor, 7
is the quotient.
CONFIDENTIAL 9
Estimate 356 ÷ 40
So, 360 ÷ 40 = 9
The basic fact is: 36 ÷ 4 = 9
The estimate of 356 ÷ 41 is 9.
356 is closer to 360.41 is closer to 40.
We have learnt to estimate quotients by using Compatible Numbers.Here we will use division facts to find a compatible number for 356
and 40.
CONFIDENTIAL 10
Divide 43 by 20.
We will solve this with the help of place-value models.
43 can be shown as 4 tens and 3 ones.We will draw rectangles to show 2 groups of 20.
STEP 1:
20 43
On paper and pencil:
CONFIDENTIAL 11
Place an equal number of tens in each group of 20 blocks.
20 43
On paper and pencil:
2
- 403
There will be 3 ones left. This is the Remainder.
STEP 2:
CONFIDENTIAL 14
12 169
On paper and
pencil: STEP 1:
12 169
1
- 124
1 tens in each group.
12 tens in used.4 tens left.
STEP 2:
12< 16. So there are enough tens.
CONFIDENTIAL 15
12 169
1
- 1249
Bring down 9 ones.49 ones in all.
STEP 3:
STEP 4:
12 169
14
- 1249
- 481
48 ones used.1 left is Remainder.
CONFIDENTIAL 17
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CONFIDENTIAL 19
4) Savio covers a distance of 180 miles driving his car. If he covers 15 miles in 1 hour, then for how many hours does he
drives?
4) 12 hours
CONFIDENTIAL 21
Find:
7) 62 ÷ 20 8) 83 ÷ 10
9) 413 by 37 10) 752 by 21
7) Q = 3, R = 2 8) Q = 8, R = 3
9) Q = 11, R = 6 10) Q = 35, R = 17
CONFIDENTIAL 22
Very Good!Let's Review
Find 4,200 ÷ 60
Here also we can apply the concept of Place value to find the solution as in the previous lesson.
42 ones ÷ 6 = 7 ones
42 tens ÷ 6 tens = 7 ones
42 hundreds ÷ 6 tens = 7 tens
42 ÷ 6 = 7
420 ÷ 60 = 7
4,200 ÷ 60 = 70
42 is the Dividend, 6 is the divisor, 7
is the quotient.
CONFIDENTIAL 23
Estimate 356 ÷ 40
We have learnt to estimate quotients by using Compatible Numbers.
Here we will use division facts to find a compatible number for 356.
356 is closer to 360.
So, 360 ÷ 40 = 9
The basic fact is: 36 ÷
4 = 9The estimate of 356 ÷ 40 is 9.
Find 169 ÷ 12
12 169
STEP 1:
12 169
1
- 124
1 tens in each group.
12 tens in used.4 tens left.
STEP 2:
12< 16. So there are enough tens.
41 is closer to 40.
CONFIDENTIAL 24
12 169
1
- 1249
Bring down 9 ones.49 ones in all.
STEP 3:
STEP 4:
12 169
14
- 1249
- 481
48 ones used.1 left is Remainder.
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