13*7=28?




13 x 7 = 28?Send D.T.
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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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