Guessing a cube root of a perfect cube in 3-5 secs

Hi!  In this post we are going to learn guessing the cube root of a perfect cube in  3-5 secs

first,we will see the cubes of first ten natural numbers if we have this in our mind we can guess cube root of any perfect cube
let me show the beauty of mathematics in cubes 
cube of 2 is 8   and  cube of 8 is ends with 2
and similarly in 3 and 7
and all last digits of the cubes are unique like
1-1
2-8
3-7
4 -4
5-5
6-6
7-3
8-2
9-9
lets  try  an example:   13824
sol: observe the last digit / units digit = 4 that means cube root contains 4 in unit digit
as the given number has 5 digits its cube root will have 2 digits
divide the number in to  parts for every three digits from right to left
13|824
find the nearest cube  to 13 that is 8 its cube root is 2
that’s it. 24 is cube root of the 13824


3 steps 3 secs :-
1) find the unit digit of the number find the unit digit
2) divide the number into parts fro every 3 digits from right to left
3) find the nearest cube to first part of the number
lets try one more example…  373248
sol:
1) unit digit =8 so unit digit of root 2
2)373|248
3) 343 is the nearest cube to 373  cube root of 343 is 7
so 72 is the cube root  that’s it ….hope you like it
(it will applicable up to 6 digits...)

please comment and share if you like...

thank you

Hi folks! In this post we are going to learn the multiplication of two digit numbers near by hundred in 3-5 seconds

 Example 97x94?




from the figure  you can easily understand  that
1) 97 is 3less than 100
2)94 is 6 less than 100
3) in the result first two digits can be found from 97-6 or 94-3 =91
4)last digits obtained from 3 x 6=18
result obtained in 5 secs   try yourself.........

if the numbers given are above 100

Example 104 x106?

the figure explains very well  
1)104 is 4 more than 100
2)106 is 6 more than 100
3)In the result first two digits can be found from 104+6 =106+4 =110
4)last digits obtained from 4 x 6=24we can use easily up to 120 if we know up to 20 tables perfectly

let's see one more example ....
Example 112 x110?

Here,
we have product of last digits 12 x10 =120 is a three digit number
So digit 1 to be added to 122 as shown in the figure....

By applying the same technique we can find squares of number from 85 to 120
By simple single line  i will present the way
note: we are taking 100 as base here(91²) = (91-9)x 100+ (9²) =8200+1 =8281
(92²) = (92-8)x 100+ (8x8) =8400+64 =8464
(93²)= (93-7)x 100+ (7x7) =8600+49 =8649

Here, we have a simple explanation..
1) 91 is 9 less than 100 so the number to be added to get last digits is 9²      
2) multiplying by 100 for understanding sake only if your thorough  directly you can write as (91-9)(9²)= 8281
 
try the remaining  up to 120
in the next post we are going to learn cubes and finding of cuberoots in fast way

multiplication of four digit numbers fast

Hi! In this post we are going to learnto multiply 4digit number in 5-10secs
Before that you need to mind these things…
1) in competition exams we need not to do whole multiplication  in order to find the result
2) if we found last two or three digits, it is enough to choose answer form given options

lets try the multiplication of 1234 &4321 
please follow the figures given below 

 

In this technique answer is going from right to left

red colored bold digit is digit found in each step
green colored digit denotes the carry numbers to be added to next digit
mostly in the third step we will get the answer
hope this figures 1-7 make you clear how to find the digits of the product 1234 and 4321


hope this figures will make you clear how to use this technique

Quantitative Aptitude Tips and Tricks

Quantitative Aptitude:

Necessary for appearing in:
IBPS BANK PO CAT,MAT,GRE,GATE ,RRB,LIC,CAMPUS RECRUITMENT,AND MANY MORE NATIONALIZED EXAMS

WHAT WE NEED TO GET THROUGH THEM?
1.SPEED
2.ACCURACY
In this blog we are going to cover almost all topics with best tips for enhance your ability in either of the requirements(speed and accuracy )
Before going to start the topics , we need to remind the things that we left at school..

 going back to the school.........:-)

MULTIPLICATION OF TWO THREE DIGIT NUMBERS in 5secs:

Problem1:   product  two numbers 121 & 310 is?
options:
a)36520
b)37510
c)35710
d)32610


sol:121 x 310...    answer going from right digit to left...
please follow this figure

this example is simple one all product yields single digit numbers
if the product gives two digit number ................
dont worry about it simply add the carry number to its next digit(right digit to left...)

see the following:
979 x 685....answer going from right digit to left...
last digit is 9x5=45, write 5 carry 4
next digit 7x5 + 9x8 = 35 + 72= 107 (+4) = 111, write 1 carry 11
next digit 9x6 + 7x8 + 9x5 = 54 + 56 + 45 = 155 (+11) = 166, write 6 arry 16
next digit 9x8 + 7x6 = 72 + 42 = 114 (+16) = 130, write 0 carry 13
next digits 9x6 = 54 (+13) = 67. Write this all in.
Answer is 670615
this type of multiplication  will be explained in 4digit multiplication in the next post