Chapter Two Lesson Two

1
Chapter Two Lesson Two
2
An adult zoo elephant eats about 87 pounds of hay
each day. A zookeeper needs to feed 4 elephants
for 28 days in February. The zookeeper has
12,000 pounds of hay. Is this enough for the
month?
87 x 28 x 4
3
Our lesson today is aboutEstimating Products

• 87 x 28 x 4

This is an example of overestimation. When you
only round factors to larger numbers, you get an
OVERESTIMATE.
An UNDERESTIMATE is when you only round factors
to smaller numbers.
90 x 30 x 5
80 x 20 x 4
13,500
6,400
90 x 30 x 4
80 x 25 x 4
10,800
8,000
100 x 30 x 4
12,000
Our estimated answer could be between 6,400 and
13,500 pounds of hay.
4
87 x 28 x 4 9,744

• Decide whether you think an
  overestimate or underestimate is necessary.

The time it will take to drive to your destination
overestimate
underestimate
The number of miles you can drive on a tank of
gas
overestimate
How much a trip will cost
underestimate
How much will fit in a suitcase
5
53 x 4 x 28
When you estimate this product, think of your
overestimates and underestimates. Your estimate
should be somewhere between these two.
60 x 4 x 30
7,200
Overestimate Underestimate
50 x 4 x 20
4,000
6,000
Check this is an accurate estimate
Your estimate
6
40 x 60 x 3 7,200 Overestimate
Underestimate 30 x 50 x 3 4,500

• 33 x 58 x 3

5,400
Your estimate
7
Estimation Practice

• 18 x 19 x 50

20,000
98 x 14 x 3
3,000
51 x 9 x 21
9,000
4 x 79 x 24
8,000