Nassia's Percents Post

Hi, this is my percents post! -Nassia


1) Key Percents:

- To find 50% of a number, divide it by 2.
- To find 10% of a number, divide it by 10.
- To find 1% of a number, divide it by 100.
- To find 25% of a number, divide it by 4.

A percent is... a number out of 100. When you break the word percent up, you get "per" and "cent, which means "per one hundred" basically.

 2) Represnting Percents

a) 180%
      
b) 12 3/4%














c) 0.7   .....???

3) Converting Decimals, Fractions, and Percents


26% -------->    26÷100= 0.26 (Decimal)
                           26/100 (Fraction)

EXPLANATION: To convert 26% into a decimal, you divide it by 100, and you get 0.26, your decimal number. To convert that into a fraction you first take 0.26, and since there are NO decimals in a fraction, you just exclude it. The same goes for the zero at the front because it has no value. Now you have 26. That will become the numerator of your decimal. To find the denominator, you look at the decimal number you found, and find the place value. The place value of 0.26 is 100. When you peice your fraction together, you get 26/100!! TA-DA!

7/10 -------->  7÷10= 0.7 (Decimal)
                         0.7X100= 70% (Percentage)

EXPLANATION: To convert 7/10 into a decimal, you divide the numerator (7) by the denominator (10). From that you get the decimal number, which is 0.7. To get the percentage, you multply the decimal you just got by 100, and you get the answer 70%.


0.024 -------> 0.024X100= 2.4% (Percentage)
                        24/10 (Fraction)

EXPLANATION: To convert 0.024 into a percentage, you have to take it and multiply it by 100. After you get your answer from that, use it to get the fraction. There are no decimals in fractions, so 2.4 turns into 24, and the place value of the decimal is 10. You get 24/10.


4) Percent of a Number ( Calulator and No Caculator)

20% of 60 ------> CALCULATOR: 0.20 X 60 = 12
                              NONE: 10% of 60 = 6           6 X 2=12


0.1% of 40 ------> CALCULATOR: 0.1x40=4
                               NONE: 0.1% is 4


250% of 400 ------> CALCULATOR: 250÷100= 2.5      2.5x400= 1,000
                                  NONE: 100% of 400 = 400
                                               100% of 400 = 400
                                                50% of 400 = 200   --> 400+400+200=1,000


5) Combining Percents


A herd of 100 caribou was moved to a new location. The population increased by 10% the 1st year, then increased by 20% the next year.

Find the population of the second year:

10÷100= 0.10 -------> 1st Year ------> 0.10x100= 10 (increase)        100+10= 110
                                     2nd year -------> 0.20x110= 22 (increase)        110=22= 132
         

You can't use 30%, because you'll end up with a different wrong number.

Trisha's Percent Post

Hi this is my percent post!!

1.

• 50% - To find 50% of a number, you divide the number by 2.

• 10% - To find 10% of a number, you divide the number by 10.

• 1% - To find 1% of a number you divide the number by 100.

• 25% - To find 25% of a number you divide the number by 4.

• A percent is a number out of 100 or a whole. 

2.

• 180%

 

•  12 3/4%

• 0.7%

3.

• 26%

To convert a percentage to a decimal you have to divide the percentage by 100.  
Percent to Decimal: 26% ÷ 100 = 0.26

To convert a percent to a fraction you will have to first convert it to a decimal number (0.26), then you cross out the zero(s) (26) to get the numerator. In order to get the denominator of the fraction, you look at the place value of the last digit in the decimal number (hundredths). 

Percent to Fraction: 26/100

                

•  7/10

To convert a fraction to a decimal, you have to divide the numerator by the denominator

Fraction to Decimal: 7 ÷ 10 = 0.7

To convert a fraction to a percent you will have to first convert the fraction into a decimal number. Then you multiply the decimal by 100 to get the percentage. 

Fraction to Percent: 0.7 x 100 = 70%

• 0.024

 To convert a decimal number into a percent, you multiply the decimal by 100. 
 Decimal Percent: 0.024 x 100 = 2.4%

To convert a decimal number to a fraction, you cross out the zero(s) (24) to get the numerator, to get the denominator you look at the place value of the last digit of the decimal number (thousandths).

Decimal to Fraction: 24/ 1000

 4.

•  20%  of 60 = 12

     Mental Math:  10% of 60 = 6            ( 10% x 60 = 600

                             10% of 60 = 6              600 ÷ 100 = 6)

                                   6 + 6 =  12

     Calculator:      20% ÷ 100 = 0.2

                             0.2 x 60 = 12

• 0.1% of 40 = 0.04

 Mental Math: 40 ÷ 10 = 4 
                         4 ÷ 100 = 0.04
                        

   Calculator:     0.1% ÷ 100 = 0.001

                          0.001 x 40 = 0.04

• 250% of 400 = 1,000

 Mental Math:   100% of 400 = 400
                          100% of 400 = 400
                            50% of 400= 200

                            400+ 400 + 200 =  1000                     

  
Calculator:      250% ÷ 100 = 2.5

                         2.5 x 400 = 1,000


 5.
 Question 7 on page 149: A herd of 100 caribou was moved to a new location. The population increased by 10% the first year and then increased by 20% the second year.

A) Find the population after the second year. 
 10% ÷ 100 = 0.1
0.1 x 100 = 10
100 + 10 = 110

20% ÷ 100 = 0.2
0.2 x 110 = 22
110 + 22 = 132

B) Explain why there was not a 30% increase in population over the two years. 

There was not a 30% increase in population over the two years because the population wouldn't be accurate, it would be less than the actual population over the two years with the 10% increase in the first year and the 20% increase in the second year. 

30% ÷ 100 = 0.3
0.3 x 100 = 30
100 + 30 = 130