Can you tell me a metod of multiplication and division that is really fast and you can make it in your head?

Question

, without calculating on a paper or something like that?

I know one for multiplication, but it does work only if you have: 12*19, or 25*24, or 58*52. It does work only if the number has the first number the same. I'm waiting for your opinions, and if you'd want me to show what I created without reading anything about this, I just wanted to know to do it much faster. I hope you understand what I mean. Thank you for your time.

Answer 1

Yes, I can tell you how to multiply any number by 0 really fast.

1 works pretty fast, too.

10 is almost as fast.

Answer 2

If the numbers are relatively small, close together, and you know the square of their average, use (a+b)(a-b) = a^2 - b^2, eg
51*49 = (50+1)(50-1)=2500-1=2,499
23*27 = 625 - 4 = 621

With 2 and 3-digit numbers, it's easier & faster to multiply from left-to-right instead of right-to-left: Add as you go instead of making a list to add:

81*26 = 1600 + 480 = 2080 + 20 = 2100 + 6 = 2106

''932 *284 = 180,000 + 6000 = 186,000 + 72000 = 258,000 + 400 = 258,400 + 2,400 = 260,800 + 3,600 = 264,400 + 160 = 264,560 + 120 = 264,680 + 8 = 264,688

It looks a lot harder than it really is. It does require a little practice, but you can find the solution faster than you can type the steps.

Yet another quick way is to "rewrite" numbers as difference instead of sums:
12*19 = 12(20-1) = 240-12 = 228, or
(10+2)*19 = 190+38 = 228.
This works well only for numbers close to multiples of 10.

Answer 3

Hi:

Here is a neat way

try factors of numbers for example 12 { use (6,2,)or ( 3,4) } times 123


123 *6= 738

then 738*2 = 1476

work good with division as well

but for more tricks and tips on Multiplication or Division get the following books :

Math Magic by Scott Flansburg - the Human Calculator
he got lot of trick for doing this

How to calculate quickly - Dover Publications

101 Quick Ways to Calculate by Nicholas E Scripture

Calculate with Jean (The Human Adding Machine)

Math-A-Magic by Laurence B. White, Meyer Seltzer,


Hope this helps

Answer 4

hee you got an example. i use this metod always and is good
for ex you have 20*34
_34*
-_ 20
-------
_680
I multiplay 2 with each 4 and three and u keep the 0
or 45*32
__45*
__32
-------
__90
_135
= 90
__135
---------
__225
I hope u understood it
I used the _ because i needed to arange the numbers