Like making 2 + 2 = 5 or somthing like that.
2007-01-27 09:54:04 · 7 answers · asked by SNL (sat night live) 4 in Science & Mathematics ➔ Mathematics
2 + 4 = 6, 1(2) +2(2) = 6, 1(2) + 2 = 6/2, so 4 = 3
2007-01-27 09:57:12 · answer #1 · answered by .......... 4 · 1⤊ 1⤋
1+2+3+4+.. n = n(n+1)/2
ie., 1 + 2 + .. 10 = 10*11/2 = 55
Useful in numerous word problems.
"10 people in a room shook hands with everyone. How many shaking of hands took place?"
ans: person 1 shook hands with 9 others
person 2 with 8 others because we've already counted his with person 1
person 3 is with 7 others
so ans = 9 + 8 + .. 1 = 9*10/2 = 45
similar question:
10 people played ping pong round-robbins style. how many games were played.
20 cities had roads connecting each other. how many roads?
legend has it that Gauss was in kindergarten when his teacher gave the class the question:
what is 1 + 2 + 3 + .. + 100: so that she could go out on an errand.
all the kids, bar Gauss, had their shoes and socks off and were tallying with fingers and toes.
Gauss decided he could do:
X = 1 + 2 + 3 + ... 100
X = 100 + 99 + 98 +. . 1
2X = 101 + 101 + 101 + .. 101 (a hundred 101s)
Therefore X = 100 * 101/2 = 5050
He gave the answer before his teacher could walk out of class and wrote himself into the history books. His teacher probably never did get to meet her boyfriend and probably died a spinster ;(
2007-01-27 18:13:41 · answer #2 · answered by astatine 5 · 0⤊ 0⤋
Find 25^2 or 55^2 by only using your head in 5 secs.
Its easy.
Multiply the one's digit of 25 and the other 25. And you should get 25....ok...add 1 to the tens digit of one of the 25 and you should get 35. Now multiply the 3 of 35 by 2 of 25 and you should get 6. Combine the 6 and 25 and .........drumroll plz.....625....25^2=625....
Samething with 55... 5*5=25....add 1 to tens digit of one of the 55 and then multiply....and you should get 30...combine....what the answer????.......3025.....55^2 equals 3025....
Its a good trick to show to all your friends.....Cheers!
2007-01-27 18:04:42 · answer #3 · answered by Anonymous · 1⤊ 0⤋
on the tables note that the answers are 0-9 going down and 0-9 coming up
9x1=09
9x2=18
9x3=27
9x4=36
9x5=45
9x6=54
9x7=63
9x8=72
9x9=81
9x10=90
2007-01-27 18:12:25 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Here is one for the ordr of operations:
P.E.M.D.A.S
This means "Please Exuse My Dear Aunt Sally"
P stands for parentheseas
E satnds for exponent
M stands for multipy
D stands for divide
A stands for addition
S stands for subtraction
You use this ofr probles like these:
8 +2 x 3 + 2
8 + 6 + 2
14 + 2
15
Hope this helps!
2007-01-27 18:47:58 · answer #5 · answered by ♥ 4 · 0⤊ 0⤋
Enter the number 31773 on a calculator and turn it upside down. You get my name.. Okay, corny and self -centered and only remotely associated with math, but I like it! LOL!
2007-01-27 18:02:21 · answer #6 · answered by Ellie S 4 · 1⤊ 0⤋
When multiplying by nines it goes 09
This size increases- - - - - -18- - - - - and this decreases
27...
2007-01-27 18:02:52 · answer #7 · answered by Josh S 2 · 0⤊ 0⤋