Monday, February 21, 2005

Math Bytes

Hi All,

Some Math bytes !

Ever Wondered how easy it is to multiply 2, two digit numbers ending with the digit 5!

Ex: 15*15 = 225 but how easily can you arrive at this answer? ever wondered it can be done in one step?

Read On..............................






Multiply both the 5's! you get 25 right? Now, multiply 1*1 and add 1 one to it = 2. So, the answer 225 :)

Similarly,
25*25 = Multiply both the 5's! Now again it gives you 25! Also, 2*2 =4 + 2 = 6. So, the answer 625 :)

and so on......................



So, try for other numbers and know the results yourself! Until next time chao!..................



Jay.

2 comments:

RR said...

Alternatively ,

for 25* 25 the math can work as follows

5*5=25
take the first digit and add 1 to the first digit to get the second.Mulitply 1 and 2 to get the resultant.In this case

1st digit = 2
2nd digit= 2+1=3
Resultant =2*3 and concontenate 25= 625

Similar approach.........

Robert H. said...

What rr says is correct, but the first method doesn't work for larger numbers:
5*5 = 25
5*5 + 2 = 27
but 55*55 doesn't equal 2725.

rr's method
5(5+1) concat 5*5 gives 3025.
That works.