Page 209 - Math Course 1 (Book 1)

Mental Math: Percents

1
Estimate % of 1219. Your Turn!
4
1 1 Find Percent of a Number Mentally
% = x 1%. 1219 is about 1200.
4 4
Find 50% of 82 mentally.
1% of 1200 is 12.
A. 41
B. 164
1 1 C. 16
Answer % of 1219 is about x12 or 3.
4 4 D. 40
Answer

Estimate 155% of 38.

155% means about 150 for every 100 or about Find 25% of 36 mentally.
15 for every 10.
A. 144
38 has about 4 tens.
B. 10
C. 90
15 × 4 = 60
D. 9

Answer 155% of 38 is about 60. Answer

Find 80% of 60 mentally.

A. 12
REAL WORLD EXAMPLE B. 50
C. 48
MONEY D. 480
A restaurant bill totals $21.35. You
want to leave a 15% tip. What is a Answer
reasonable amount for the tip?

$21.35 is about $21. A reasonable tip is 15%

15% = 10% + 5% Move the decimal point 1
10% of $21 is $2.10 place to the left Estimate Percents
Estimate 38% of 400.
5% of $21 is $1.05 5% is one half of 10%.
A. 100
So, 15% is about $2.10 + $1.05 or $3.15 B. 152
C. 160
A reasonable amount for the D. 80
Answer
tip would be $3.
Answer

1
Estimate % of 2482.
5
A. 25
B. 4.964
C. 4
D. 5
Answer

201