Lesson 9 : Some fun

1729 is known as Hardy Ramanujam Number.  (There is a wiki article here). Reading the article all the way down, I read an interesting part that the Japanese Scientist Masahiki Fujiwara found out.

1729 –> add the numbers and you get 1+7+2+9=19

Reverse 19 and you get 91. 19x91=1729. According to him only 2 more numbers other than 1729 show this property. One is 81 and other is 1458. I decided to write a small piece of code to verify this.

for x=10 to 9999 ' find the sum of numbers first ' reverse this number ' multiply it and you should get the original number     n=x     s=0     while (n>0)         s=s+(n mod 10)         n=int(n/10)     wend 'reverse s, call it rs     if s<10 then         rs=s     else         rs=(s mod 10) * 10 + int(s/10)     end if     if (s*rs = x) then         wscript.echo x     end if    next

 

C:\scripts>nos.vbs //nologo 81 1458 1729 C:\scripts>

And yes there are only 3 numbers.