Human Calculators.

Elijah accomplished a pretty amazing feat during math on Wednesday. He performed the multiplication of two 2-digit numbers in his head. At the time, most of us were trying to wake up from the nice nap called a first free so we didn't really notice this.

As Ms. Mariner brought it up, it finally started to sink in. THE MULTIPLICATION OF TWO 2-DIGIT NUMBERS WITHOUT A CALCULATOR.!!!!!!!!!!!!!!!!!!!!!!! That is awesome to be able to do that.
 How did he do that, you might ask...

I really don't know how he did it. He could have already done the problem on his calculator and just remembered the answer or he did it in his head.

I wonder if there is a special way to be able to do that:
                            -Wrote memorization probably won't help in the long run, because what are the chances that you will see that exact number combination again?!?!?
                            -Are there any fancy tricks that you can do: if the number that you need is 32*80 multiply the 32*8 and add the zero on the end. But what if the number is 67*59? There is no zero in that number that you can add at the end.
                            -Maybe the distributive property is how you do it. I don't know how to do it that way so I will go on so I don't confuzzle you.
                            - How else could you multiply two 2-digit numbers in your head and get it correct? (I'll have to get back to you on this one.)

 

                             -Algebra tiles (like ones shown above) are also a way to do such multiplication in your head. Say that the blue tile has sides of 3 and 3. The green tiles have sides of 3 and 1 and each of the little yellow blocks have sides of 1 and 1. The area of the 5 green tiles are 5(3 x 1) or 15 units squared plus the area of blue block (9) plus six little blocks (6 because 1 x 1=1) The area of the combined figure is 30 units squared. You gust add all the little areas in the big figure together to get the total area of the large figure. 

                         - Another way to multiply any number by 11 is first you take the other number (not 11) and add the digits together to get a number. and stick it between the digits of the other number (not 11) and there is the answer. Example: 54*11 --> 5+4 =9 --> 594!

                                - This simple trick works for the multiplication of all two digit numbers by two digit numbers. Line up the numbers going vertically, but read horizontally, with the other number making a box. Going down, multiply the tens place and the ones place and remember them. Then you are going to multiply the top ten's place with the bottom ones place, and the top ones place with the bottom ten's place. Add those two numbers together. Put them in order starting with the ten's place, then the crisscrossed numbers and then finally the ones place. If the middle number is 10+, leave the ones place of that number and add the number in the ten's place to the number that you got when you multiplied the Original tens place. Then you will have the answer. (See pic)

How did he do it? Maybe he's a genius with a very high IQ and has the ability to do that!!!!!!! Or maybe he even used one of these tricks to get the answer. Or maybe he's just a sophomore that can get math easier than others in our calculator-dependent society. :)