Using Number Sense to Solve Equations

1
Using Number Sense to Solve Equations
COURSE 2 LESSON 2-2
Find the solution of h 18 54 3, 36, 62,
or 72.
You can test each number by substituting h in the
equation.
Since the equation is true when you substitute 72
for h, the solution is 72.
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2
Using Number Sense to Solve Equations
COURSE 2 LESSON 2-2
Use mental math to solve each equation.
a. s 9 5
b. 4z 28
What you think What number minus 9 equals
5? Since 14 9 5, s 14.
What you think What number times 4 equals
28? Since 4 7 28, z 7.
c. g 7 11
What you think What number plus 7 equals
11? Since 4 7 11, g 4.
What you think What number divided by 6 equals
5? Since 30 6 5, c 30.
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3
Using Number Sense to Solve Equations
COURSE 2 LESSON 2-2
The weight of a packing crate is 14.65 lb. The
crate and its contents together weigh 85.21 lb.
Estimate the weight of the contents.
The contents of the crate weigh about 70 lb.
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4
Using Number Sense to Solve Equations
COURSE 2 LESSON 2-2
Solve each equation. Use mental math or
estimation. 1. q 15 25 2. 6r
42 3. 17.25 s 21.4 4. 8 5. m
39.8 101.03
q 40
r 7
t 10
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