# Basic Math

Updated on June 29, 2013

## Basic Math

Hello, I am Marc Guberti, and I love mathematics. I want to teach young students the basics (or elementary) of math such as multiplication tables and more! I offer a quiz for young students to take to improve their math skills. I teach addition, subtraction, multiplication, division, and more! I hope that you learn a lot from my lens.

If you have any questions, please make a comment!

## Multiplication Tables-1

1x1=1

1x2=2

1x3=3

1x4=4

1x5=5

1x6=6

1x7=7

1x8=8

1x9=9

1x10=10

1x11=11

1x12=12

Any number multiplied by 1 will not change (the is the multiplicative identity). Remember that this is called the Multiplicative Identity because any number times 1 will still keep its identity.

## Decimals and Fractions

Here are some important decimals and fractions to know.

1/4= .25

1/3= .33

1/2= .50 or .5

2/3= .66

*2/4=1/2= .5

3/4= .75

1/5= .2

2/5= .4

3/5= .6

4/5= .8

1/8= .125

3/8= .375

1/10= .1

3/10= .3

*2/4 is simplified to 1/2 and is the same decimal!

## Percents

### Similar to Decimals and Fractions

You might have seen the picture for my last post with a percent for 1/2 as well. I decided to start fresh with percents because they can help you with your daily lives figuring out the tip, discount, and more, but that will be later.

An important thing to know about a decimal is this:

Ex: One half (1/2) is equal to .5, however, .5 can also equal .500000...... because all of those 0s do not change the value of the decimal. It will still be the fraction 1/2. So, 50/100 is simplified to 5/10 which is 1/2! The decimal never changes no matter how many 0s you add AFTER the last number in the decimal (in this case 5).

Now, do you see that percent sign? It has 2 circles. Now, think of those circles as decimal points.

TO MAKE A DECIMAL INTO A PERCENT, MOVE THE DECIMAL POINT TWO PLACES TO THE RIGHT!

Ex:

1/2= .5

.5 moved two places to the right is 50

.5, 5, 50.

That's how we got .5=50%!

## Multiplication Tables-2

2x1=2

2x2=4

2x3=6

2x4=8

2x5=10

2x6=12

2x7=14

2x8=16

2x9=18

2x10=20

2x11=22

2x12=24

If you multiply a number by two, you are adding that number twice. For example 12x2 is the same thing as saying 12+12. Both get a final answer of 24. Eventually, you will need to memorize this rule for longer multiplication problems like 8x7. Adding the number 7 8 times on paper would take too much work. For all multiplication, it is important to memorize the basics.

## Squared Numbers

A squared number is a number times itself. Most people should know up to 15 squared, but some know up to 20 squared without the use of a calculator! If a number has a small 2 over it, then it is being squared. If 1 was being squared, it would be 1x1. If it has a small 3 over it, then the number is being cubed. If 1 was being cubed, it would be 1x1x1. Anything else is to power of something.1 to the power of 4 is 1x1x1x1. Does that make sense? Ok, now let's go through some of the essential numbers that you should know how to square without a calculator.

1 squared (1x1)=1

2 squared (2x2)=4

3 squared (3x3)=9

4 squared (4x4)=16

5 squared (5x5)=25

6 squared (6x6)=36

7 squared (7x7)=49

8 squared (8x8)=64

9 squared (9x9)=81

10 squared (10x10)=100

11 squared (11x11)=121

12 squared (12x12)=144

13 squared (13x13)=169

14 squared (14x14)=196

15 squared (15x15)=225

16 squared (16x16)= 256

17 squared (17x17)=289

18 squared (18x18)=324

19 squared (19x19)=361

20 squared (20x20)=400

## Multiply Big Numbers with a lot of 0s

### The Easiest Way

2,000x4,000

Can you do it?

If the answer is no, then I can help.

If you see a number with a couple of 0s, then this is what you do. Multiply the numbers that aren't 0s first. So, 2x4=8. So, we got that down, but what about all of those 0s? Well, 8 was your answer for 2x4. Just add al of the 0s you see from BOTH numbers after the 8. So, your final answer is 8,000,000 (the 8 and 6 zeros after it). Now, multiply that into your calculator. You should get the same results.

Now you are prepared to take the quiz!

3x1=3

3x2=6

3x3=9

3x4=12

3x5=15

3x6=18

3x7=21

3x8=24

3x9=27

3x10=30

3x11=33

3x12=36

4x1=4

4x2=8

4x3=12

4x4=16

4x5=20

4x6=24

4x7=28

4x8=32

4x9=36

4x10=40

4x11=44

4x12=48

## Finding the Y-Intercept and the Slope

How long does it take you to find the Y-Intercept and Slope? Does it take a minute or 30 seconds? Well, today, I will show you how to find the Y-Intercept and Slope of any equation written in slope intercept form in 1-5 seconds! The slope intercept form of an equation is y=mx+b. m represents the slope and b is the Y-Intercept. So, in the equation y=2x+4, the slope is 2 and the Y-Intercept is 4. If the equation is y=x+4, you might stumble. Why is that? Well, there is no number in front of x. Visibly, there is no number in front of x, but it is linked to 1 by multiplication. When a variable stands alone, you must put a 1 on that variable because it is linked by multiplication. So, the slope of y=x+4 is 1 and the Y=Intercept is still 4. So, the next point would be (1,5). However, what if you had a fraction. Let's say y=1/4x+2. We know the Y-Intercept is 2 and the slope is 1/4, but what would the next point be? Since 2 is the Y-Intercept, we start at (0,2). To figure out points for a slope of 1/4, you must use the rise/run formula. The numerator of a fraction is the rise and the denominator of a fraction is a run. You rise (go up) 1 space and you run (go across to the right) 4 spaces. So, after (0,2), your next point would be (4,3).

If you see an equation (slope intercept form) that shows y=3x or anything without a Y-Intercept, the Y-Intercept is always 0! Just plug in the numbers. y=3x. Then 0=3(0). Then 0=0. So, that would be labeled (0,0).

Some Slope Intercept Forms can be written as Y= -3x+1. A point then GOES DOWN 3 units and 1 unit to the right. OR, the point goes 3 units up, but 1 unit to the LEFT. Both are correct.

5x1=5

5x2=10

5x3=15

5x4=20

5x5=25

5x6=30

5x7=35

5x8=40

5x9=45

5x10=50

5x11=55

5x12=60

## Good Math Textbooks

All of these math textbooks contain good information that are rich with knowledge for you or your child to learn. I recommend these books to you to get a good start on your next math subject.

6x1=6

6x2=12

6x3=18

6x4=24

6x5=30

6x6=36

6x7=42

6x8=48

9x9=54

6x10=60

6x11=66

6x12=72

7x1=7

7x2=14

7x3=21

7x4=28

7x5=35

7x6=42

7x7=49

7x8=56

7x9=63

7x10=70

7x11=77

7x12=84

## Finding the Area

Here are some formulas to find the area of various 2-Dimmensional shapes. You must memorize these formulas!

Square: A=s squared

Rectangle: A=lw

Trapezoid: A=((b1+b2)h)/2

Triangle: A=(bh)/2

Circle: A=Pi r squared

Parallelogram: A=bh

KEY:

l=length

w=width

b=base

h=height

s=side

8x1=8

8x2=16

8x3=24

8x4=32

8x5=40

8x6=48

8x7=56

8x8=64

8x9=72

8x10=80

8x11=88

8x12=96

## Angles

Any angle that measure LESS THAN 90 degrees is called an ACUTE ANGLE.

Any angle that measures EXACTLY 90 degrees is called a RIGHT ANGLE.

Any angle that measures MORE THAN 90 degrees, but LESS THAN 180 degrees is called an OBTUSE ANGLE.

Any angle that measures EXACTLY 180 degrees is called a STRAIGHT ANGLE.

Those are all of the angles (excluding straight angles, but that is just a line).

9x1=9

9x2=18

9x3=27

9x4=36

9x5=45

9x6=54

9x7=63

9x8=72

9x9=81

9x10=90

9x11=99

9x12=108

132

3

59

28

10

2

## Do You Have Any Questions? - Or do you want to give feedback?

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• fullofshoes

6 years ago

Great lens, Marc. It's so nice to see a young person interested in "real" math. It's nice to know that somebody under the age of 40 can actually count out change. ~very blessed~

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