Construction Math
Section 2: Whole numbers
What is a whole number?
Complete units without fractions or
decimals.
Digits and place value
5,316,247
Positive and negative numbers
Positive numbers are greater than zero
 Negative numbers are less than zero
 ZERO
Neither negative nor positive

Adding and Subtracting
Sum
Difference
Sum and word problems

Different key words in word problems to
indicate addition
◦
◦
◦
◦
◦
Total
Sum
Together
Altogether
Combine
Difference and Word Problems

Different key words in word problems to
indicate subtraction
◦
◦
◦
◦
◦
◦
◦
Minus
Difference
How much less
How much more
Amount of decrease
Amount of increase
How much is left
Test your skill
In calculating a bid for a roof restoration,
the contractor estimates that he will need
$847 for lumber, $456 for roofing shingles
and $169 for hardware. What is his total
cost?
 What operator (+,-,*,/) do you need?
 Addition— “total”
 $1,472

Test your skill
A plumbing contractor allotted $4,265 in
his bank account to complete three
residential jobs. If he estimates Job 1 to
cost $1032, Job 2 to cost $943, and Job 3
to cost $1,341, how much money will he
have left in the account for unexpected
change orders?
 What operator (+,-,*,/) will we use?
 Subtraction– “have left”
 $949

Profit, the bottom line

If we are looking to make a profit, we
must make sure that the cost of labor and
parts is not more than the amount we
charge. Therefore, it is vitally important
to be able to estimate and calculate cost
versus amount of money available
Multiplying and dividing
Product
Quotient
Product
24
x 16
Quotient


When dividing whole numbers, often they
do not divide evenly. The left over part is
called the remainder.
Why is remainder important? Useful for
calculating supplies. If I need 45 feet of rope
and I have a selection of 30 foot sections, I
can divide and find that I need 1.5 (or 1 and
a remainder of 15) sections of rope. One
section is not going to cut it, I’m going to
need 2 sections. When looking at supplies, I
must round up, no matter my remainder.
Quotient
48 386
Multiplication and Word Problems

Look for key words to indicate the
appropriate operation
◦ Product
◦ Times
◦ When given a single quantity—determine
multiple quantities
Division and Word Problems

Key words… do we detect the pattern here?
KEY WORDS KEY WORDS KEY WORDS
◦
◦
◦
◦
◦
◦
◦
◦
Quotient
Divide
For 1
For each
Separate
Per
A
When given multiple quantities—determine
single quantity
Supplies Relationship
Test your skill
Your supervisor sends you to the truck
for 180 feet of electrical wire. When you
get there, you find that the coils of wire
come in 15ft lengths. How many coils of
wire will you need to bring back?
 What operator (+,-,*,/) will you use?
 Division
 180/15=12

Test your skill, follow up


You get back to your supervisor and he tells
you that for the next job, you will need 200
ft of the same wire that comes in 15 ft coils.
How many coils will you need?
200/15=13.33333333
◦ It is impossible to simply take 0.3333333 coils
back.
◦ When purchasing and calculating supplies, we
must always round up to the nearest whole
number.
◦ You will need to take back 14 coils in order to
get the job done
Test your skill
A crane rental company charges $383 per
day, $1,224 a week (5 day week), and
$3,381 a month.
 How much would it cost to rent the
crane for 3 days?

◦ $1,149 (3x383) [3 x daily]

12 days?
◦ $4,596 (12 x 383) [12 x daily rate]
◦ $3,214 ((2 x 1,224) + (2 x 383) [(2 x
weekly)+(2 x daily)]
That pesky crane again
A crane rental company charges $383 per
day, $1,224 a week (5 day week), and
$3,381 a month.
 How much would it cost to rent the
crane for 17 days?

◦ $6,511 (17 x 383) [17 x daily rate]
◦ $4,438 ((3 x 1,224) + (2 x 383)) [(3 x weekly)
+ (2 x daily)
◦ $3,381 (1 x 3,381) [1 x monthly]
Perimeter
The distance around the outside of any
closed shape, such as a rectangle, circle, or
square
 Measure all sides and add them together

4m
P=4+4+1+1=10
1m
Perimeter of irregular figures

Houses are not square boxes.
40 ft
P=40+40+20+15+20+25=160
25 ft
40 ft
20 ft