[i][b] hooooooooooooooooooooooooooooo
hoooooooooooooooooooooooooooo
i say after doing mathematics because it is hard sub
to multiply any three number by 11just dooooooo this thing e.g
453
last no 3 will come in last then
2and3 no is 5 3 we will add=8
now.we will add 1and2 no is 4 5 we will add=9
now right the first no 4
ans ==========4983
(453*11=4983)magic )
Aviral Tiwari
Nice ones. I posted my own multiplication shortcuts on Discrete Ideas.
Hai Ido not about shortcuts But there are formulae to find the sum OR term in arithmetic progression First term=a difference=d n=No of terms l=last term Then n=((l-a)/d)+One
t(n)=a+(n-one)d ,sum(n)=n/2(2a+(n-one)d)OR
s(n)=n/2(a+l) For odd nos The sum is n to the power 2 (to Leilani)
Does anyone agree with me that one of the greatest roadblocks keeping 5th - 12th graders from using mental math is that they use calculators too much?
If you want to have fun doing mental math you can use this:
http://www.nixroot.com/icompute/
A really a fun way to stay sharp! 
I LOVE IT !!!
nice…
I LOVE IT !!!
Anthony Lota — January 20
Neat perspective.
I was sitting at dinner and, being the quiet type, contemplated the relation between numbers squared. Here are some thoughts and observations:
-13^2= 169, while 31^2= 961, it would seem every number (except the exponent) is visually flipped.
-14^2= 196, while 41^2= 1681, this may seem somewhat of a stretch, but imagine 196 as 18(16), where 16 is one decimal place. The principle above applies.
-15^2= (14+1)^2= 14^2 + 2(14) + 1= 196 + (28 + 1)= 225, once you find a square, just add 2x+1 to its square to get the next integer squared.
-34^2= (30+4)^2= 30^2 + 2(30)4 + 4^2= 900 + 240 + 16= 1156, its easy to break it into tens and ones.
Not sure if this is helpful, just thought it may spark some epiphanies or allow slightly quicker squaring.
Just thought of something else, sorry, I’m new here. Over the years, i always wondered how 1 square foot equaled 144 square inches. I realized not only were the measurements squared, but so were their proportions. This lead to a discovery of “dimensional scaling” i call it.
-If one square has half the width AND height of another, its area is (1/2 * 1/2)= (1/2)^2= 1/4 the area of the other, yet a cube with half dimensions would be (1/2 * 1/2 * 1/2)= (1/2)^3= 1/8 the volume. Notice the pattern? The space occupied (area, volume, etc.) of a relative object is the (space occupation of the reference object) * (scale^dimensions).
-This works for circles and spheres when you consider the dimensional occupation of the object first (circles: dimensions=2).
-It can also apply to varying scales: a cube with width/2, height/3, depth/4 equals (whd)(1/2)(1/3)(1/4).
I really hopes this helps, it allowed me to answer an ACT question faster and easier.
hai
very nice!!!
I think they should be teaching our children to use an abacus in elementary school…I learned how to use one at that age and I have always used most of these mental math shortcuts my whole life. Not because someone showed me, I have just always been able to reduce things to simple math, and visualize the abacus…I’m just sayin…
@Mike: Yep, I think having more hands-on learning techniques could be helpful in developing an intuition for math.
I’ll be very much thankful if you could explain how the series / order arrived :
- 8 11 19 25 31 47
- 2 20 21 22 26 49
nice
VERY NICE…GN