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13 x 7 = 28?

Yes it's true!

How can this be?

let's take a look!

ok, first, look at this problem...

     13
   x  7
   ----

now, multiply the three 7 times and place the result like this...

     13
   x  7
   ----
     21

next, multiply the one 7 times and place the result like this...

     13
   x  7
   ----
     21
      7

add the 21 and 7...

     13
   x  7
   ----
     21
   +  7
   ----
     28

and you get 28. therefore, 13x7=28.

WHAT? You want me to prove it by division? Well, here goes...

    ---
   7)28

now let's start with the 2.

    ---
   7)28

now, how many times does seven go into 2?

zero. you cannot divide 7 into 2.

so, you go to the 8.

    ---
   7)28

now, how many times does seven go into 8?

one. so, place the 1 like this...

      1
    ----
   7) 28

put the 7 under the 28 like this...

       1
    ----
   7) 28
       7

and subtract the 7 from the 28...

      1
    ----
   7) 28
    -  7
      --
      21

next, how many times does 7 go into 21?

3. so you put the 3 to the right of the 1, put the product of 3x7 under the 21, and...

      13
    ----
   7) 28
    -  7
      --
      21
    - 21
      --
       0

you have no remainder, so the answer is an integer.

therefore, 7 into 28 is 13.

WHAT? You want me to prove it by addition? well, consider this...

     13
   + 13
   + 13
   + 13
   + 13
   + 13
   + 13
   ----

now, add the 3's together: 3. 6. 9. 12. 15. 18. 21.

     13
   + 13
   + 13
   + 13
   + 13
   + 13
   + 13
   ----
     21

... add the 1's: 22. 23. 24. 25. 26. 27. 28.

     13
   + 13
   + 13
   + 13
   + 13
   + 13
   + 13
   ----
     21
   +  7
   ----
     28

there! that proves that...

13 x 7 is 28!

d.t.

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