Compatible
numbers are numbers you can
divide easily. You can use compatible numbers to estimate
quotients.

Think of a
division fact that is like the numbers you are dividing. 
Estimate:
181
5.
Estimating
with Compatible Numbers
Estimate: 
46 

6 
Think: 
What
number times 6 has a product close to 46? 

8
x 6 = 48 
So, 
46 

6 is
about 8. 


Find
where the quotient begins.
Estimate: 
312 

5 

Try
dividing hundreds. 

5
< 3 
Not
enough hundreds 
Try
dividing tens. 

5
> 31 
Enough
tens 

So
the quotient begins in the tens place. 
Find
the first digit of the quotient. 
Think:
About how many 5s in 31? 
5
x 5 = 25
too small 
5
x 6 = 30
31 is between 25 and 35. Try 6. 
5
x 7 = 35
too big 
Since
you are estimating, write zeros for the other digits. 
is about 60. 


If
two numbers are compatible, one divides the other evenly. 
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