6 Awesome Mental Math Tricks Your Teacher Failed to Show You

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mental math tricks shortcuts

Learn these easy mental math tricks and impress all your friends and family.

They’ll think you’re a genius and they’ll finally show you the respect you deserve. AND shame on your teacher… sheesh… teaching you the hard way to do math.  It’s about time someone showed you an easier way.  Some of these mental math tricks may seem a little tricky at first to learn, but once you get the hang of them you’ll be doing math in you head in no time!

Impress your friends, your family… a new lover?  New fancy cars are an outdated technique to capture the attention of someone special, use your new mind powers instead!  The best way to remember these mental math tricks and shortcuts is practicing them.

1 Multiply any Two Digit Number by 11

In this example we’ll choose:  [math]36*11=396[/math]

  1. Add the two digits of 36.  [math]3+6=9[/math]
  2. Simply place the answer of 9 between the digits of 36.  For Example: 3 9 6

[math]396[/math]  It’s that easy!

Remember : In case you happen to get a 10 or above in step 1, you must remember to carry the one over.

For Example:

[math]49*11=539[/math] is achieved by adding both digits [math]4+9=13[/math].  Then we place the answer of 13 in the middle 4 13 9 . HOWEVER, you can only have a single digit in the middle, so you have to carry the 1 over to the 4, resulting in [math]539[/math].

Try an Alternate Way: See video on multiplying large numbers by 11

2 Square any number ending in 5

In this example we’ll choose:  [math]35^2=2025[/math]

  1. Multiply the first digit by itself plus 1. [math](3*4)=12[/math]
  2. Add 25 on the end of your answer in step 1.  [math]1225[/math]

This one is really simple to get the hang of.  Square the first digit, add the same digit to it, and then add 25 on the end of it and Presto!

3 Divide any number by 5

In this example we’ll choose:  [math]2253/5=450.6[/math]

  1. Multiply by 2. [math]2253*2=4506[/math]
  2. Divide by 10 (move decimal place one place to the left).  [math]4506/10=450.6[/math]

Love this one.  Really what we are doing is multiplying 2253 by 1/5 or 2/10 which means multiply by 2 and divide by 10 which is a super easy way vs dividing by 5.

4 Multiply any number by 5

In this example we’ll choose:  [math]486*5=2430[/math]

  1. Divide by 2. [math]486/2=243[/math]
  2. Multiply by 10 (move decimal place one place to the left).  [math]243*10=2430[/math]

Same principle as dividing by 5. What we are doing is multiplying 486 by 5/1 or 10/2 which means multiply by 10 and divide by 2 which is a super easy way vs multiplying by 5.

5 Multiply up to 19 x 19

In this example we’ll choose:  [math]14*13=182[/math]

  1. Add together 14 and the 3 from the 13.  [math]14+3=17[/math]
  2. Add a 0 on the end of 17.  [math]170[/math]
  3. Multiply the ones digits together.  [math]4*3=12[/math]
  4. Add Steps 1 and 3 together.  [math]170+12=182[/math]

This one might seem a little hard at first, but once you get the hang of it, it’s really easy.

6 Square any two digit number

In this example we’ll choose 23 to square.  [math]23^2[/math]

  1. First Step is to square both digits separately. [math]2^2=04[/math] & [math]3^2=09[/math]
  2. Place the two numbers together side by side and remember this number –  ex. 0409  (9 or any other single digits will be displayed with 0 in front ex. 09)
  3. Take the two digits of the number you are squaring ( 2 and 3)  and multiply them.  [math]2*3=6[/math]
  4. Double the answer of 6 and  multiply by 10  [math]6*2*10=120[/math]
  5. Add 409 to 120.  [math]409+120=529[/math]

This one requires more steps to remember so it’s a little more difficult to remember.

Try an Alternate way:  See video on quickly squaring numbers

It might take you awhile but after a few practice problems, you’ll improve speed!

The Best App I use for Mental Math Tricks:

For more Mental Math Tricks, visit these great sites below:

  1. Businessinsider.com: 10 Mental Math Tricks
  2. Glad2teach.co.uk – Fast Math Calculation Tricks
  3. Cut-the-knot.org – Rapid Arithmetic
  4. Angelfire.com – Fantastic Math Tricks
  5. Student-Tutor.com – Mental Math Tricks

If you’re a visual learner, here are some great videos on mental math tricks:

 

Visit these youtube channels: