Download Add and Subtract Rational Numbers

Objective
The student will be able to:
1. add and subtract rational numbers.
2. compare and order rational
numbers.
SOL: none
Designed by Skip Tyler, Varina High School
Find the sum.
1) -2.304 + (-0.26)
Line up the decimals and add (same signs).
-2.564
5 3
2) 
8  4 
5 6 

8  8 
Get a common denominator
and subtract.
1

8
Find the difference.
3)
5  3 
 
9  5 
Change subtraction to
adding the opposite.
5  3 
 
9  5
Get a common denominator.
25 27 

45 45 
Subtract and keep sign of
the larger number.
2
45
Find the difference.
1 6
4) 
2 7
1  6 
 
2  7 
7 12 

14  14 
5
14
Change subtraction to
adding the opposite.
Get a common
denominator and subtract.
5) Solve 6.32 – y if y = -3.42
Substitute for y: 6.32 - (-3.42)
6.32 + 3.42
9.74
1.
2.
3.
4.
-3.2
-2.8
2.8
3.2
Find the solution
6.5 – 9.3 = ?
Answer Now
Find the solution
1.
2.
3.
4.
5
.
12
1
7
3
7
11
12
2  1 
   ?
3  4 
Answer Now
A rational number is a number
that can be written as a fraction.
How can these be written as a fraction?
3
3=
1
11
3
2  
4
4
Inequality Symbols
Symbol
<
>
≠
≤
≥
=
Meaning
is less than
is greater than
is not equal to
is less than or equal to
is greater than or equal to
is equal to
Ordering Rational Numbers
2 ways to order from least to greatest
1. Get a common denominator
2. Change the fractions to decimals
(numerator  demoninator)
Which rational number is bigger?
4
3
or
11 8
1) Get a common denominator.
32 33

88 88
2) or convert the fraction to a decimal.
0.363 < 0.375
4
3
<
11 8
Which rational number is bigger?
7 11
or
4 6
1) Get a common denominator
42 44
<
24 24
2) or convert to a decimal
1.75 < 1.83
7 11

4 6
Which symbol makes this true?
5
3
__
7
4
1. <
2. >
3. =
Answer Now
Which symbol makes this true?
-2
-1
__
4
9
1. <
2. >
3. =
Answer Now