15 Minute Math

This presentation will review different math skills that will This presentation will review different math skills that will help you with every day math problems.help you with every day math problems.

Each lesson takes approximately 15 minutes to do. Almost Each lesson takes approximately 15 minutes to do. Almost anyone can find an extra 15 minutes out of his or her day, anyone can find an extra 15 minutes out of his or her day, whether it be during breakfast or right before bed. In just whether it be during breakfast or right before bed. In just under 3 weeks, you can review all the TABE Computation under 3 weeks, you can review all the TABE Computation Math sections.Math sections.

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

15 Minute Math15 Minute Math

15 Minute Math15 Minute Math

DecimalsDecimalso Lesson 1Lesson 1 – What Are Decimals? – What Are Decimals?o Lesson 2Lesson 2 – Addition & – Addition &

SubtractionSubtractiono Lesson 3Lesson 3 – Multiplication – Multiplicationo Lesson 4Lesson 4 – Division – Division

FractionsFractionso Lesson 5Lesson 5 – What Are Fractions? – What Are Fractions?o Lesson 6Lesson 6 - Addition & - Addition &

Subtraction (no whole #s)Subtraction (no whole #s)o Lesson 7Lesson 7 – Addition & – Addition &

Subtraction (with whole #s)Subtraction (with whole #s)o Lesson 8Lesson 8 – Multiplication & – Multiplication &

DivisionDivision PercentagesPercentages

o Lesson 9Lesson 9 – Converting Decimals – Converting Decimals to Fractions to Percentsto Fractions to Percents

o Lesson 10 Lesson 10 – Calculating the Part– Calculating the Parto Lesson 11 Lesson 11 – Cross-Multiplication – Cross-Multiplication

MethodMethod

IntegersIntegerso Lesson 12 Lesson 12 – Addition & Subtraction– Addition & Subtractiono Lesson 13 Lesson 13 – Multiplication, – Multiplication,

Division, & Absolute ValueDivision, & Absolute Value AlgebraAlgebra

o Lesson 14 Lesson 14 – Adding & Subtracting – Adding & Subtracting VariablesVariables

o Lesson 15 Lesson 15 – Multiplying & Dividing – Multiplying & Dividing VariablesVariables

o Lesson 16 Lesson 16 – Square Roots– Square Roots Order of OperationsOrder of Operations

o Lesson 17 Lesson 17 – Please Excuse My – Please Excuse My Dear Aunt SallyDear Aunt Sally

o Lesson 18 Lesson 18 – Order of Operations – Order of Operations with Variableswith Variables

Practice TestsPractice Testso Lesson 19 Lesson 19 – Practice Test #1– Practice Test #1o Lesson 20 Lesson 20 – Practice Test #2– Practice Test #2

15 Minute Math – Decimals15 Minute Math – DecimalsLesson # 1 – Lesson # 1 – What Are Decimals?

This lesson explains how to This lesson explains how to read and work with decimals.read and work with decimals.

ProblemProblem: You work in a medical lab and you need to tell your : You work in a medical lab and you need to tell your coworker how much medicine you need.coworker how much medicine you need.

““I need two tenths of a gram of insulin.”I need two tenths of a gram of insulin.”

Saying numbers correctly can ensure everyone is talking about the Saying numbers correctly can ensure everyone is talking about the same thing.same thing.

Decimals are numbers that are less than 1 but greater Decimals are numbers that are less than 1 but greater than 0than 0

0 < 0.1 < 1 (0.1 is between 0 and 1, so it is a decimal)0 < 0.1 < 1 (0.1 is between 0 and 1, so it is a decimal)

They appear to the right of the decimal pointThey appear to the right of the decimal point

whole number decimal whole number decimal

39.139.1

““39” is the whole number part39” is the whole number part

““.1” is the decimal part.1” is the decimal part

““39.1” is read…39.1” is read…

““Thirty-nine and one tenth”Thirty-nine and one tenth”

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


te

n-th

ousa

nds

thou

sand

shu

ndre

dste

nson

este

nths

hund

redt

hsth

ousa

ndth

ste

n-th

ousa

ndth

s

1 2 3 4 5 6 7 8 9

10,000.+ 2,000.+ 300.+ 40.+ 5.+ .6+ .07+ .008+ .0009 12,345.6789

The “3” is in the hundreds column, so there are “3 hundreds”. If all the other numbers were a 0, then the number would be 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.)

Remember, decimals have a “th” at the end of their names.



To read a number…To read a number…

For example: 20.045 is read, “Twenty and forty-five For example: 20.045 is read, “Twenty and forty-five thousandths.”thousandths.”

0.2 = 0.20 = 0.200 but…0.2 = 0.20 = 0.200 but… 0.2 = “two tenths”0.2 = “two tenths” 0.20 = “twenty hundredths”0.20 = “twenty hundredths” 0.200 = “two hundred 0.200 = “two hundred

thousandths“thousandths“

tenthshundredths

thousandths

1) R

ead

the

whole

num

ber p

art

2) W

here

you

see

the

decim

al p

oint

, say

“an

d”

3) R

ead

the

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4) S

ay th

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n na

me

whe

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th

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num

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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.

Try it yourselfTry it yourself

What numbers are these?What numbers are these?Three and two hundredths = 3.02Three and two hundredths = 3.02Forty and two thousandth = Forty and two thousandth = Twelve and twelve hundredths =Twelve and twelve hundredths =Eighty and eighty ten-thousands =Eighty and eighty ten-thousands =

How do you say these numbers?How do you say these numbers?37.03 = Thirty-seven and three hundredths37.03 = Thirty-seven and three hundredths9.04 = 9.04 = 20.040 = 20.040 = 100.01 = 100.01 =

Which of these are true:Which of these are true:A) 2.01 = 2.010A) 2.01 = 2.010 B) 2.01 = 2.001B) 2.01 = 2.001C) 2.001 = 2.100C) 2.001 = 2.100 D) 2.10 = 2.010D) 2.10 = 2.010E) 2.10 = 2.100E) 2.10 = 2.100 F) 2.0010 = 2.001F) 2.0010 = 2.001

Forty and two thousandth = 40.002Forty and two thousandth = 40.002Twelve and twelve hundredths = 12.12Twelve and twelve hundredths = 12.12Eighty and eighty ten-thousands = Eighty and eighty ten-thousands =

80.008080.0080

9.04 = nine and four hundredths9.04 = nine and four hundredths20.040 = twenty and forty thousands20.040 = twenty and forty thousands100.01 = one hundred and one 100.01 = one hundred and one

hundredthhundredth

A, E, and F are trueA, E, and F are true

End of Lesson 1


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15 Minute Math – Decimals15 Minute Math – DecimalsLesson # 2 – Lesson # 2 – Addition & Subtraction

Line up the decimals pointsLine up the decimals points Put zeroes in the blank spaces to help you see what Put zeroes in the blank spaces to help you see what

you’re addingyou’re adding

24.3 + 18.45 24.3 + 18.45 24.30 24.30 18.62 – 3.8 18.62 – 3.8 18.62 18.62

+18.45+18.45 - 3.80- 3.80

42.7542.75 14.82 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.

117

/


All numbers have a decimal point, even if you can’t All numbers have a decimal point, even if you can’t see it.see it.

For example, $15 can also be written as $15.00For example, $15 can also be written as $15.00

20 + 4.02 20 + 4.02 20.00 20.00 100 – 25.783 100 – 25.783 100.000100.000

+ 4.02+ 4.02 - - 25.78325.783

24.0224.02 74.21774.217

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

19


99 9

/ / / / /

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 find.


2.89 + 1.5 =2.89 + 1.5 = 20.6 + 10.9 = 20.6 + 10.9 = 3.13 + 9 = 3.13 + 9 =

20 + 8.2 = 20 + 8.2 = 9.373 + 3.34 = 9.373 + 3.34 = 9 + 2.8 = 9 + 2.8 =

12.99 – 8.1 = 12.99 – 8.1 = 19 – 3.2 = 19 – 3.2 = 2.933 – 1.2 = 2.933 – 1.2 =

8.4 – 5.555 = 8.4 – 5.555 = 20 – 2.5 = 20 – 2.5 = 100 – 2.66 = 100 – 2.66 =

2.89 + 1.5 = 2.89 + 1.5 = 4.394.39 20.6 + 10.9 = 20.6 + 10.9 = 31.531.5 3.13 + 9 = 3.13 + 9 = 12.1312.1320 + 8.2 = 20 + 8.2 = 28.228.2 9.373 + 3.34 = 9.373 + 3.34 = 12.71312.713 9 + 2.8 = 9 + 2.8 = 11.811.812.99 – 8.1 = 12.99 – 8.1 = 4.894.89 19 – 3.2 = 19 – 3.2 = 15.815.8 2.933 – 1.2 = 2.933 – 1.2 = 1.7331.7338.4 – 5.555 = 8.4 – 5.555 = 2.8452.845 20 – 2.5 = 20 – 2.5 = 17.517.5 100 – 2.66 = 100 – 2.66 =

97.3497.34 End of Lesson 2


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15 Minute Math – Decimals15 Minute Math – DecimalsLesson # 3 – Lesson # 3 – Multiplication

Don’t worry about the decimal until you’re done Don’t worry about the decimal until you’re done multiplying everythingmultiplying everything

First multiply, and then count up the places to the right of First multiply, and then count up the places to the right of the decimal point and put the decimal in the answer.the decimal point and put the decimal in the answer.

3.51 x 1.4 3.51 x 1.4 351 351

××1414

14041404

+3510+3510

49144914

3 decimal places

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)

4.9144.914

So, 3.51 x 1.4 = 4.914!So, 3.51 x 1.4 = 4.914!


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

2.3 2.3 × 0.0002× 0.0002 23 23

× 2× 2

4646

5 decimal places

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.

0.000460.00046

So, 2.3 x 0.0002 = 0.00046!So, 2.3 x 0.0002 = 0.00046!


5 decimal places

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

shift the decimal left 4 places (if youshift the decimal left 4 places (if you move the decimal point rightmove the decimal point right(don’t see the decimal point it’s at the end)(don’t see the decimal point it’s at the end) 2 spaces (100 has 2 0’s)2 spaces (100 has 2 0’s)

297 297 × 0.0001× 0.0001 = 0.0297 = 0.0297 2.309 2.309 × 100 = 230.9× 100 = 230.9

4 decimal places

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 or smaller.




27.2 × 9.2 =27.2 × 9.2 = 3.2904 × 0.22 = 3.2904 × 0.22 = 62.5 × 12.8 = 62.5 × 12.8 =

38 × 0.25 = 38 × 0.25 = 0.034 × 0.026 = 0.034 × 0.026 = 8.02 × 2.1 = 8.02 × 2.1 =

2.04 × 0.001 = 2.04 × 0.001 = 589 × 100 = 589 × 100 = 10.2 × 1.2 = 10.2 × 1.2 =

0.34 × 0.5 = 0.34 × 0.5 = 5.89 × 100 = 5.89 × 100 = 9.9999 × 0.01 = 9.9999 × 0.01 =

27.2 × 9.2 = 27.2 × 9.2 = 250.24250.24 3.2904 × 0.22 = 3.2904 × 0.22 = 0.7238880.723888 62.5 × 12.8 = 62.5 × 12.8 = 80080038 × 0.25 = 38 × 0.25 = 9.59.5 0.034 × 0.026 = 0.034 × 0.026 = 0.0008840.000884 8.02 × 2.1 = 8.02 × 2.1 = 16.84216.8422.04 × 0.001 = 2.04 × 0.001 = 0.002040.00204 589 × 100 = 589 × 100 = 58,90058,900 10.2 × 1.2 = 10.2 × 1.2 = 12.2412.240.34 × 0.5 = 0.34 × 0.5 = 0.170.17 5.89 × 100 = 5.89 × 100 = 589589 9.9999 × 0.01 = 9.9999 × 0.01 = 0.0999990.099999

End of Lesson 3

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15 Minute Math – Decimals15 Minute Math – DecimalsLesson # 4 – Lesson # 4 – Division


Remind yourself of the steps you need to take when Remind yourself of the steps you need to take when dividingdividing

1.1. DivideDivide

2.2. MultiplyMultiply

3.3. SubtractSubtract

4.4. Bring down Bring down oneone

more numbermore number

and do it againand do it again

8821|17226321|172263

8821|17226321|172263 -168-168

8821|17226321|172263 -168-168 44

8821|17226321|172263 -168-168 4242

8203820321|17226321|172263 -168-168 4242 -42-42 0606 - 0- 0 6363 -63-63 00

Step 1 - Move the decimal of the divisor (outside the house) Step 1 - Move the decimal of the divisor (outside the house) as far to the right as you canas far to the right as you can

Step 2 - Move the decimal of the dividend (inside the house) Step 2 - Move the decimal of the dividend (inside the house) by the same number of spacesby the same number of spaces

Step 3 - Move the decimal straight up onto the answer lineStep 3 - Move the decimal straight up onto the answer line

Step 4 - Divide like normalStep 4 - Divide like normal

ProblemProblem

8.91 8.91 ÷÷ 3.33.3

Steps 1 & 2Steps 1 & 2

3.3 |8.91 3.3 |8.91 33 |89.1 33 |89.1

Step 3Step 3 .. 33 |89.133 |89.1

Step 4Step 4 2.72.7 33 |89.133 |89.1 - 66- 66 231231 - 231- 231 00

Think of the division sign, | , like a house. With all division problems, the first number goes inside the house (the 8.91) and the second goes outside the house (3.3). If you forget, think about a problem you know. 10 ÷ 2 ÷ 2 = 5. You wouldn’t say 10 = 5. You wouldn’t say 10 | 2. To work it out you’d say 2 |10 (2 goes into 10.)


ProblemProblem

8.91 8.91 ÷÷ 0.00330.0033


0.0033 |8.91 0.0033 |8.91 33 |89100. 33 |89100.

Step 3Step 3 .. 33 |89100.33 |89100.

Step 4Step 4 2700.2700. 33 |89100.33 |89100. - 66- 66 231231 - 231- 231 00

ProblemProblem

8.91 8.91 ÷÷ 0.33 0.33


0.33 |8.91 0.33 |8.91 33 |891. 33 |891.

Step 3Step 3 .. 33 |891.33 |891.

Step 4Step 4 27.27. 33 |891.33 |891. - 66- 66 231231 - 231- 231 00

Move the decimal 2 places to the right

Move the decimal 2 places to the rightFill in the empty spaces with zeroes




3.2 ÷ 64 = 60.8 60.8 ÷ 19 = = 187.53 187.53 ÷ 3 ==

3.2 3.2 ÷ 6.4 = = 60.8 60.8 ÷ 0.19 = = 187.53 187.53 ÷ 0.03 ==

32 32 ÷ 6.4 = 6.4 = 0.608 0.608 ÷ 0.19 = = 18753 18753 ÷ 0.3 ==

32 32 ÷ 0.00064 = = 608 608 ÷ 1.9 = = 0.0018753 0.0018753 ÷ 0.3 ==

3.2 ÷ 64 = 0.05 60.8 60.8 ÷ 19 = 3.2= 3.2 187.53 187.53 ÷ 3 = 62.51= 62.51

3.2 3.2 ÷ 6.4 = 0.5= 0.5 60.8 60.8 ÷ 0.19 = 320= 320 187.53 187.53 ÷ 0.03 = 6251= 625132 32 ÷ 6.4 = 56.4 = 5 0.608 0.608 ÷ 0.19 = = 3.23.2 18753 18753

÷ 0.3 = 62510= 6251032 32 ÷ 0.00064 = 50000= 50000 608 608 ÷ 1.9 = 320= 320 0.0018753 0.0018753 ÷ 0.3 = =

0.0062510.006251

End of Lesson 4

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15 Minute Math