Fiftyfine _ Minute _ Math

15 Minute Math
This presentation will review different math skills that will
help you with every day math problems.
Each lesson takes approximately 15 minutes to do. Almost
anyone can find an extra 15 minutes out of his or her day,
whether it be during breakfast or right before bed. In just
under 3 weeks, you can review all the TABE Computation
Math sections.

Look for the Professor. He has special hints to help
make working the math problems faster and easier.


15 Minute Math






Decimals
o
Lesson 1 – What Are Decimals?
o
Lesson 2 – Addition &
Subtraction
o
Lesson 3 – Multiplication
o
Lesson 4 – Division
Fractions

o
Lesson 5 – What Are Fractions?
o
Lesson 6 - Addition &
Subtraction (no whole #s)
o
Lesson 7 – Addition &
Subtraction (with whole #s)
o
Lesson 8 – Multiplication &
Division
Percentages
o
Lesson 9 – Converting Decimals
to Fractions to Percents
o
Lesson 10 – Calculating the Part
o
Lesson 11 – Cross-Multiplication
Method









Integers

o
Lesson 12 – Addition & Subtraction
o
Lesson 13 – Multiplication,
Division, & Absolute Value
Algebra
o
Lesson 14 – Adding & Subtracting
Variables
o
Lesson 15 – Multiplying & Dividing
Variables
o
Lesson 16 – Square Roots
Order of Operations
o
Lesson 17 – Please Excuse My
Dear Aunt Sally
o
Lesson 18 – Order of Operations
with Variables
Practice Tests
o
Lesson 19 – Practice Test #1
o
Lesson 20 – Practice Test #2


15 Minute Math – Decimals
Lesson # 1 – What Are Decimals?

This lesson explains how to
read and work with decimals.
Problem: You work in a medical lab and you need to tell your
coworker how much medicine you need.
“I need two tenths of a gram of insulin.”
Saying numbers correctly can ensure everyone is talking about the
same thing.


15 Minute Math – Decimals
Lesson # 1 – What Are Decimals?


Decimals are numbers that are less than 1 but greater than 0
0 < 0.1 < 1 (0.1 is between 0 and 1, so it is a decimal)



They appear to the right of the decimal point
whole number

decimal

39.1
“39” is the whole number part
“.1” is the decimal part


“39.1” is read…

“Thirty-nine and one tenth”

 “0.1” is the same
thing as “.1”. “.1” is just
a lazy way of writing the
number.


15 Minute Math – Decimals
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Lesson # 1 – What Are Decimals?

1
10,000.
+ 2,000.
+
300.
+
40.
+
5.
+

.6
+
.07
+
.008
+
.
0009

2

3

4

5

6

7

8

9

The “3” is in the hundreds column,
 Remember,
so there are “3 hundreds”.

decimals have a

If all the other numbers were
“th” at the end of
a 0, then the number would be
their names.
00300.0000, which is 300 (three hundred.)

The “7” is in the hundredths column,
so there are “7 hundredths.”
If every other number were a 0, then the number
would be 00000.0700, which is 0.07 (seven hundredths.)


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15 Minute Math – Decimals

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Lesson # 1 – What Are Decimals?

For example: 20.045 is read, “Twenty and forty-five
thousandths.”
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 Extra zeroes to the far right of
a decimal don’t change the
value, but they do change how
you pronounce the number.

0.2 = 0.20 = 0.200 but…
0.2 = “two tenths”

0.20 = “twenty hundredths”
0.200 = “two hundred


15 Minute Math – Decimals
Lesson # 1 – What Are Decimals?
Try it yourself
What numbers are these?
Three and two hundredths = 3.02
Forty and two thousandth =
Twelve and twelve hundredths =
Eighty and eighty ten-thousands =
How do you say these numbers?
37.03 = Thirty-seven and three hundredths
9.04 =
20.040 =
100.01 =
Which of these are true:
A) 2.01 = 2.010
C) 2.001 = 2.100
E) 2.10 = 2.100

End of Lesson

B) 2.01 = 2.001
D) 2.10 = 2.010
F) 2.0010 = 2.001

Click for answers:
Forty and two thousandth = 40.002

Twelve and twelve hundredths = 12.12
Eighty and eighty ten-thousands =
80.0080
9.04 = nine and four hundredths
20.040 = twenty and forty thousands
100.01 = one hundred and one
hundredth


15 Minute Math – Decimals
Lesson # 2 – Addition & Subtraction


15 Minute Math – Decimals
Lesson # 2 – Addition & Subtraction



Line up the decimals points
Put zeroes in the blank spaces to help you see what you’re
adding

24.3 + 18.45



1

24.30
+18.45

42.75

18.62 – 3.8



7

1
18.62
/
- 3.80
14.82

 When adding, don’t forget to carry when
numbers add up to more than 10.
 When subtracting, don’t forget to borrow if
the top number is smaller than the bottom
number.


15 Minute Math – Decimals
Lesson # 2 – Addition & Subtraction


All numbers have a decimal point, even if you can’t
see it.
For example, $15 can also be written as $15.00
99

9 91

/// //
20 + 4.02

 20.00
+ 4.02
24.02

100 – 25.783

Remember when you’re borrowing,
you can’t borrow from nothing (zero).
Make sure you borrow all the way
over to the first non-zero number you



100.000
- 25.783
74.217

 Even if you don’t
see the decimal
point, it’s actually
at the end.
100 = 100. =
100.00

15 Minute Math – Decimals
Lesson # 2 – Addition & Subtraction
Try it yourself
2.89 + 1.5 =

20.6 + 10.9 =

3.13 + 9 =

20 + 8.2 =

9.373 + 3.34 =

9 + 2.8 =

12.99 – 8.1 =

19 – 3.2 =

2.933 – 1.2 =

8.4 – 5.555 =

20 – 2.5 =

100 – 2.66 =

End of Lesson

Click for answers:

2.89 + 1.5 = 4.39
20 + 8.2 = 28.2
12.99 – 8.1 = 4.89
1.733

20.6 + 10.9 = 31.5
9.373 + 3.34 = 12.713
19 – 3.2 = 15.8

3.13 + 9 = 12.13
9 + 2.8 = 11.8
2.933 – 1.2 =


15 Minute Math – Decimals
Lesson # 3 – Multiplication


15 Minute Math – Decimals
Lesson # 3 – Multiplication




Don’t worry about the decimal until you’re done multiplying
everything
First multiply, and then count up the places to the right of the
decimal point and put the decimal in the answer.

3.51 x 1.4  351

×14
1404
3 decimal +3510
4914
places






 4.914

So, 3.51 x 1.4 = 4.914!

first, multiply 351 by 4
then, multiply 351 by 10
then, add up the numbers
last, since there are a total of
3 decimal places in the
problem, start from the right
and move the decimal 3
places to the left in the
answer (the problem has 3
decimal places and so does
the answer)


15 Minute Math – Decimals
Lesson # 3 – Multiplication



Remember to only count numbers to the RIGHT of the
decimal point.

2.3 × 0.0002  23
×2
46  0.00046
5 decimal
places

5 decimal
places

So, 2.3 x 0.0002 = 0.00046!



Sometimes you may
see
.00046 instead of
0.00046. Both are
right, but it’s more
common to put a 0
in the ones place.


15 Minute Math – Decimals
Lesson # 3 – Multiplication


There are some shortcuts you can take if you’re
multiplying by a multiple of 10. Multiples of 10 are things
like 10, 100, 1000 and also things like 0.1, 0.01, 0.001,
etc.

shift the decimal left 4 places (if you
(don’t see the decimal point it’s at the end)

297 × 0.0001 = 0.0297
4 decimal
places

move the decimal point right
2 spaces (100 has 2 0’s)

2.309 × 100 = 230.9

Try not to think about if you’re moving the
decimal to the right or the left. Think if
you need to make the number larger
(because you’re multiplying by a number
bigger than 1) or if you need to make the
number smaller (because you’re
multiplying by a number between 0 and
1). Then move the decimal point in the
direction that will make the number bigger


15 Minute Math – Decimals

Lesson # 3 – Multiplication
Try it yourself
27.2 × 9.2 =

3.2904 × 0.22 =

62.5 × 12.8 =

38 × 0.25 =

0.034 × 0.026 =

8.02 × 2.1 =

2.04 × 0.001 =

589 × 100 =

10.2 × 1.2 =

0.34 × 0.5 =

5.89 × 100 =

9.9999 × 0.01 =

End of Lesson

Click for answers:
27.2 × 9.2 = 250.24

38 × 0.25 = 9.5
2.04 × 0.001 = 0.00204
0.34 × 0.5 = 0.17

3.2904 × 0.22 = 0.723888 62.5 × 12.8 = 800
0.034 × 0.026 = 0.000884 8.02 × 2.1 = 16.842
589 × 100 = 58,900
10.2 × 1.2 = 12.24
5.89 × 100 = 589
9.9999 × 0.01 =


15 Minute Math – Decimals
Lesson # 4 – Division


15 Minute Math – Decimals
Lesson # 4 – Division


Remind yourself of the steps you need to take when
dividing
8
8203
1. Divide
21|172263
21|172263
2.

3.

4.

Multiply

8
21|172263
-168

Subtract

8
21|172263
-168
4

Bring down one
more number
and do it again

8
21|172263
-168
42

-168
42
-42
06
- 0

63
-63
0


15 Minute Math – Decimals
Lesson # 4 – Division

Step 1 - Move the decimal of the divisor (outside the house) as far to the
right as you can
Step 2 - Move the decimal of the dividend (inside the house) by the same
number of spaces
Step 3 - Move the decimal straight up onto the answer line
Step 4 - Divide like normal

Problem
8.91 ÷
3.3

Steps 1 & 2

Step 3
.
 33 |89.1

Step 4
2.7
 33 |89.1
 3.3 |8.91  33 |89.1
- 66

 Think of the division sign, | , like a house. With all
231
division problems, the first number goes inside the
- 231
house (the 8.91) and the second goes outside the house
0
(3.3).
 If you forget, think about a problem you know. 10 ÷ 2


15 Minute Math – Decimals
Lesson # 4 – Division
Problem

Steps 1 & 2

8.91 ÷ 0.33  0.33 |8.91  33 |891.

Step 3
.
 33 |891.

Move the decimal 2 places to the right

Problem

Steps 1 & 2

Step 3

Step 4
27.
 33 |891.
- 66
231
- 231
0

Step 4
.
2700.
8.91 ÷ 0.0033 0.0033 |8.91  33 |89100.  33 |89100.  33 |89100.
- 66
Move the decimal 2 places to the right
231
Fill in the empty spaces with zeroes
- 231
0


15 Minute Math – Decimals
Lesson # 4 – Division
Try it yourself
3.2 ÷ 64 =

60.8 ÷ 19 =

187.53 ÷ 3 =

3.2 ÷ 6.4 =

60.8 ÷ 0.19 =

187.53 ÷ 0.03 =

32 ÷ 6.4 =

0.608 ÷ 0.19 =

18753 ÷ 0.3 =

32 ÷ 0.00064 =

608 ÷ 1.9 =

0.0018753 ÷ 0.3 =

End of Lesson

Click for answers:
3.2 ÷ 64 = 0.05
60.8 ÷ 19 = 3.2
187.53 ÷ 3 = 62.51
3.2 ÷ 6.4 = 0.5
60.8 ÷ 0.19 = 320
0.03 = 6251
32 ÷ 6.4 = 5
0.608 ÷ 0.19 =
3.2

187.53 ÷
18753 ÷ 0.3