Page 16 - Ramanujan Yatra

Mathematical derivation of the number trick 1
Let the initial number be x; as per the instruction of the number trick 1, the step- wise computations are as follows:
Step 1: x+1
Step 2: 2x+2
Step 3: 2x+5
Step 4: 10x+25
Step 5: 10x+25+y (0<y<10)
The final sum F=10x+25+y
Now, if we subtract 25 from ‘F’, we get 10x+y
From the above, y is the unit place as y lies between 1 and 9. So, it’s very easy to identify y.
If we subtract or remove y from 10x+y and divide it by 10, we will get x (the initial number).
As x was presumed to be a whole number, this works for any x.
The readers are encouraged to investigate other mentioned tricks and find the mathematical derivation.
Few number tricks/games were exemplified so that you can develop your own game. The tricks are demonstrated based on Number Theory which is one of the oldest branches of mathematics. It mainly treats factoring and divisibility, and, of paramount importance, prime numbers. The pureness of Number Theory had also captivated Srinivasa Ramanujan. He contributed many remarkable results on Number Theory, which are still effective, popular and useful.
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Dr Primal Acharjee is professor at National Institute of Technology Durgapur.
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Ramanujan
YATRA