MULTINOMIAL EXPANSION TUTORIAL

Hello readers, we have recorded our first tutorial video and you can check it out on YouTube :

MULTINOMIAL EXPANSIONS TUTORIAL

We hope you guys like it. Feel free to leave your valuable remarks and suggestion in the comment box below.

PS- To check out more tutorials (non Math), check out our friend's blog : LINK

KEEP ON MATHEMATING!!

DIGITAL ROOT- ADD EM' UP!!

The concept of digital root is one of the most neat and easy concept in Mathematics. It helps explain many problems and further exemplifies the beauty of Math.

Digital Root of any number is the smallest single digit number that one obtains upon adding all the numbers present in a number. The digital root of 39, for instance is 3+9=12=1+2=3.

Digital Root showcases the beauty of Mathematics because the numbers of all the major sequences and series, like squares, cubes, Fibonacci series et al show a repetitive pattern in their digital root:                      

SQUARES

SQUARE	DIGITAL ROOT
1	1
4	4
9	9
16	7
25	7
36	9
49	4
64	1
81	9
100	1
121	4
144	9
169	7

               

If one observes closely, the digital root starts showing a repetition after 9, i.e. a set of 9 consecutive square numbers shows this repetitive pattern. So, the next set showing this pattern will be from 10-18, then 19-28 and so on...

CUBES

CUBE	DIGITAL ROOT
1	1
8	8
27	9
64	1
125	8
216	9
343	1
512	8
729	9
1000	1
1331	8
1728	9

Cubes follow an even shorter pattern; a set of only 3 consecutive cubes i.e. 1-3, 4-6 and so on...   

INTERESTING FACTS

·     

•     If you are careful enough, you might have seen that if 9 is added to any number ‘n’, the digital root of the sum will be equal to digit root of ‘n’. In simpler words, the addition of 9 to a number doesn't produce a change in the digital root.
• 
  
•     The above fact helps us locate a multiple of 9. So if someone asks you for a multiple of 9 closest to the number 37218, simply obtain the digital root of 37218 (3) and then you have two options, you can either add 6 to get 9, or subtract 3 from the number; but because we are concerned with the closest number, we must subtract 3, which gives us 37215 whose digital root is 9, hence proving that it is a multiple of 9. This particular method is very useful in larger numbers

·       FUN FACT- 

      After lots of adding up and messy calculations, we both found out that 14 or FOURTEEN is the first number whose digital root is equal to the digital root of the numerical values of the alphabets of its spellings!!! They both equal 5!

We encourage our readers to perform their own operations and share any observations with the Mathematics world via our blog!!

                

SOLUTION TO STAIRWAY TO HEAVEN

Here is the solution to our riddle ‘STAIRWAY TO HEAVEN’.

‘STAIRWAY TO HEAVEN’ is our adaption of the notoriously famous MONTY HALL PROBLEM. But, in that there is no devil; only a timid game show host. There are two goats and a car in the original problem.

The simple answer is that the man should switch. Switching would actually increase the probability of the new door by 33%, thus raising it to 66%.

The video below will give an intuitive explanation of the problem, so do watch it.

Monty Hall problem solution video

However, it must be noted that this is a case of probability, switching doesn't necessarily translate into winning. There is still a 33% chance that the door you have selected has the prize. Switching only decreases the odds of losing, not eliminate them!!

'STAIRWAY TO HEAVEN'- A Mathematics riddle!

STAIRWAY TO HEAVEN is our adaption of a famous mathematics problem.

Suppose there is a man who just passed away (died!), and accidentally he has been sent to ‘hell’. There, he meets a sadistic devil who gives him a chance of escaping hell in order to go to ‘heaven’.

 But there is a catch, the person must choose a specific door which holds the ‘STAIRWAY TO HEAVEN’.

He presents the problem to the man:

There are 3 doors, two contain ultimate demolition and the last door holds the STAIRWAY. You must choose the door containing the stairway in order to escape.

The man eventually chooses a door, unaware of what it holds.

The devil who knows what is behind each door opens a door that doesn’t hold the STAIRWAY.

After revealing this door, he offers the man a choice: He can either stay on the door he has chosen or switch to the door that is now left.

So, considering the fact that the devil doesn’t want the man to go to heaven, the question arises; SHOULD THE MAN MAKE THE SWITCH OR STAY ON THE DOOR THAT HE HAS CHOSEN??

KINDLY TYPE IN YOUR ANSWERS OR VIEWS IN THE COMMENT BOX BELOW (please give mathematical explanation to you answers), the solution will be revealed next week, so stay tuned!!!

Calculations made easier...

If calculating squares was a tedious job, calculating the difference of squares can be an even tougher task especially if there are bigger numbers involved. 

However, there is a neat trick that we have found which can produce the desired answer without actually calculating the squares.

There are two approaches, one is the one developed by us and the other one is more conventional, but equally effective.

• ·       The 1^st method involves generalizing the equation of differences of squares:  Let ‘n’ be the greater number and ‘n-d’ be the smaller number where‘d’ is the difference between these two numbers. Then, (n) ²-(n-d) ² = n²-(n²+d²-2dn) = 2dn-d². Hence we can express the difference between two squares via this simple expression (2dn-d²). The best thing is that now we need not calculate the squares of the bigger numbers involved, we just have to calculate the square of the difference which would be much smaller. 

Eg. 21²-12² (n=21 d=9) Using 2dn-d²

2(9) (21)-(9)²=378-81=297

In case there is a negative number involved, one need not consider the negative sign for the difference, because square of a negative number is a positive number.

(15)²-(7)² = (15)²-(-7)²

• ·       The 2^nd method makes use of the identity [a²-b²= (a+b) (a-b)]. This method too saves the hassle of calculating the squares individually and is especially useful if there are small differences involved.

Eg. 80²-78²= (80+78) (80-78) =158x2=316

Squaring numbers-The better way!! contd..

This article is an extension to our fist article: ‘Squaring numbers-The better way!!’ We will demonstrate how to calculate squares using the simple identity-

(a+b)²=a²+2ab+b²

This method is useful as it helps to break up the number into a multiple of 10 whose square is pretty use to find.

Eg. (76)²= (70+6)²=70²+2(70)(6)+6²=4900+840+36=5776

By splitting 76 into 70 and 6, we were able to calculate its square quickly, by simply using the identity.

THE GOLDEN TRIPLETS

Even though there exist infinitely many Pythagorean triplets, the most unique ones are those originating from 3, 4 and 5. 

It is known that:

3² +4² =5²

6²+8²=10²

9²+12²=15²

We can generalize these triplets in the form:

(3n) ²+ (4n) ²= (5n) ² 

Where ‘n’ is any whole number >0.

Let 3n=a  4n=b  5n=c 

It is observed that (c/a) = (5/3) = φ ≈ 1.66= Golden Ratio

Using the above formula, we can use various values of ‘n’ to find infinitely many such ‘golden triplets’

We have named them golden triplets because they follow the golden ratio.

For information about the golden ratio, please visit
http://en.wikipedia.org/wiki/Golden_ratio