Estimating 10's Places
What place is the 4 in in 40
tens
What is the difference between Standard Algorithm and Area Models? What is the same?
Area Models = Uses boxes to multiply digits and add them together
Standard Algorithm = Uses only numbers to multiply the digits and add them together
***They get the same answer AND both multiply/add***
It is the answer in a division problem
When we want to get to a number with a larger denominator we want to ....?
DO NOT SOLVE.... EX 1/2 = ?/4
Multiply
When we want to get to a number with a smaller denominator we want to ....?
DO NOT SOLVE.... EX 2/4 = ?/2
Divide
What is an easy way to solve this?
4,000 * 300
Take off the 0's and multiply 3*4 = 12... now add together the 0's... (?),000 + (?)00 = (?)00,000 ... 4,000 * 300 = 1,200,000
What did this student do wrong?
They forgot to add a 0 when multiplying by the tens place.
Estimate the Quotient
291 divided by 44
300 divided by 50 = 6
Solve Using Multiplication:
2/3 = ?/12
2/3 = 8/12
Use Bar model to solve:
2/8 = ?/4
Top box:
2 of the eight boxes are shaded
Bottom box:
1 of the four boxes are shaded... for every 1/4 we have 2/8
Place these points from least to greatest:
10,000, 10, 100, 1,000
Why do they have these values? (think placement tables)
10, 100, 1,000, 10,000
Each 0 is a tens places making the ones with more 0s larger (think placement table)
What am I doing wrong? 24x36
2 4
3 l 6 l 12 l
6 l 12 l 24 l
18 + 36 = 54
I forgot to make the 2 into a 20 and the 3 into a 30
Estimate the quotient.
607 ➗ 22
600➗20= 30
Solve:
3/4 = ?/8
3/4 = 6/8
Solve:
2/12 = ?/6
2/12 = 1/6
What is an easy way to solve this?
40,000 divided by 2,000
Take off the 0's and Divide 4/2 = 2... now subtract the 0's... (?)0,000 - (?),000 = (?)0 ... 40,000 divided by 2,000 = 20
Use Standard Algorithm to solve:
634 x 21
13,314
Estimate the Quotient
153 ➗36
150 ➗ 30 = 5
Use a Bar Model to solve:
2/3 = ?/6
Top box:
2 of the 3 are shaded
Bottom box:
4 of the 6 are shaded... for every 1/3 we have 2/6
Solve using Division
8/16 = ?/8
8/16 = 4/8
When rounding, what determins if I round up or down?
EX... 47 -> ? 523 -> ?
The half way point. For 10s it is always 5 which 5 or more make the value go up.
Use Area Models to solve this equation:
672 x 315
211,680
Give an estimate and find the quotient
Estimate: 100 / 20 = 5
Quotient: 4 R:15
As we get to a LARGER denominator, what do we do to get more pieces? (Do we want to BREAK or COMBINE? Think of our KitKats.)
We want to break... even though we are multiplying these fractions, the pieces get smaller so we get more of them.
As we get to a SMALLER denominator, what do we do to get less pieces? (Do we want to BREAK or COMBINE? Think of our KitKats.)
We want to combine... even though we are dividing these fractions, the pieces get larger so we have less of them.