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• Welcome to MooMooMath Today we are going to learn tricks with fractions.

• This video covers all 7 Trick number one,the criss cross method.

• This is an easy way to add two fractions without working to hard to find a common denominator

• The first step is to multiply the denominators together.

• 4x6=24 Now you will use what we call the "Criss-Cross Method" 6x3 =18 and 4 x 1 = 4 . Add these

• together to get the numerator which equals 18+4=22 for the numerator.

• Bring the 24 over and then you just reduces to 11/12 and that is our final answer.

• So that is the criss- cross method for adding fractions.

• A con of this method is that it is a shortcut and you are not learning the actual reasons

• for everything.

• We will just multiply the denominator which is 4x5=20 Now we will figure out our multiplies.

• I take 20 which is my new denominator and divide it by the original denominator4

• So 20 divided by 4 =5 So the first fraction I will multiply by 5 and the second fraction

• I will multiply by multiplier of 4.Once I multiply by those my numbers my denominator

• becomes a 20,but my numerator becomes a 10 + 12 and that becomes 22/20,which reduces

• to 11/10 or you can change this fraction to a mixed number by dividing by 10 which equals

• 1 1/10. and this is my final answer as a mixed number.

• Fraction trick number 3 KCF which is the Keep it,Change it Flip it method. and you use this

• to divide fractions.

• Lets look at the two fractions a/b divided by c/d You will now use Keep Change Flip to

• divide this fraction.

• You will take the first fraction and keep it.

• That is what the K stands for.

• The C stands for change and you will change from division to multiplication.

• The F stands for flip it,and you take the reciprocal of the last fraction.and it becomes

• d/c.

• Now from here you just multiple the fractions straight across and end up with ad/bc.

• Here is a quick example with numbers.

• Take 1/2 divided by 3/4 I keep the 1/2.I change the division to multiplication,and I flip

• the 3/4 to 4/3 I then multiply straight across and end up with 4/6 and reduce the answer

• and end up with 2/3 To reduce the fraction I'm just dividing by a common factor 2.

• That is how I use trick 3 Keep it Change it Flip it Rule.

• Trick # 4 Knowing the lingo.

• We are going to learn some terms in fractions.

• What is a vinculum?

• It is the line between the numerator and your

• denominator.

• The top of the fraction is the numerator and the bottom is the denominator,and the bar

• in the middle is a vinculum.Now you know the word for that bar between the 2 numbers when

• you divide.

• Trick 3 5 The Ladder Method This is very useful when you are given two

• numbers and you are trying to find the greatest common factor (GCF) or the least common multiple

• (LCM) Some people call this the cake method.Let's take 16 and 24.

• I will draw a bar underneath.

• A sideways L Next I will look for a prime factor that will divide evenly into both numbers.

• 2 will divide into both numbers and I get 8 and 12.

• Then draw a new line,and find a prime factor that will divide into these two numbers.

• 2 goes again 2 goes into 8 4 times,and goes into 12 6 times.

• Draw a new bar and find a new prime factor.

• 2 goes a third time 4 divided by 2 is 2 and goes into 6 3 times.

• I now do not have another prime factor.

• so I put a 1.

• So what do I have left.

• On the left side I have multiple these prime numbers together 2x2x2x1= 8 and this is my

• greatest common factor.

• that divides both into 16 and 24.

• Now to find my LCM I will take the first list of prime numbers plus my remainder and multiply

• all those numbers.

• 2x2x2x1x2x3 = 2x2=4 4x2=8 8x2=16 16x3=48 and

• that is my least common multiple (LCM) Trick #6 This is called the circle method.

• It is used to turn a mixed number into an improper fraction.

• We will start at the denominator and multiple in a circular direction.

• So I will take 2x3 and multiply this first.

• I then will take this result and add the numerator.So this will be 2x3 =6 plus 1 is 7,which becomes

• my new numerator and I keep my denominator a 2.

• The 31/2 becomes 7/2 42/3 3x4 =12 and then add 2 which becomes

• 14/3 That is my circle trick to convert.

• Trick # 7 Is just to memorize.

• Try to be familiar with these 12 fractions and their decimal equivalents you will have

• a good number sense of where numbers should fall between the value of 0 and and 1.

• So the best thing I can tell you is to get some flashcards,go on quizlet and they may

• be on quizlet and become familiar with these fractions.

• 1/4 =.25 The way I remember the ones with a denominator of 4 is think of quarters If

• I 1 quarter I have 25 cents.

• If I have 3 quarters I have 75 cents.

• A 1/2 is .50 or half a dollar.

• 1/5 is .20 because it takes 5 twenty's to make whole.

• Now the thirds fall in another family.

• 1/3 = .333 repeating.but 2/3 = ,333 doubles which is .666 repeating.

• 3/5 is just adding .20 to 2/5 and add .20 to 3/5 and get .80 . We are adding .20 each

• time.

• The 8ths are a little tricky to remember.

• 1/8 is .125 and 3/8=.375 5/8 =.625 and 7/8 = .875 These are the trickiest to remember.

• Get comfortable with these.

• Try to write the patterns and write these fractions down and improve your number sense.

• This helps and when you see a whole number like 5.375 you know that is really 5 3/8

• Those are your 7 fraction tricks to remember.

• Hope this video helped.

Welcome to MooMooMath Today we are going to learn tricks with fractions.

# 7種捷徑，讓你在創紀錄的時間內解決分數問題。 (7 shortcuts for solving fractions in record time)

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Coco Nut 發佈於 2021 年 01 月 14 日