## Fun with Number Theory — Pre-RMO

Here is an elementary number theory problem which can be looked upon as practice problem for pre-RMO or even RMO or just plain fun with math.

**Problem: **

Find the least number whose last digit is 7 and which becomes 5 times larger when this last digit is carried to the beginning of the number.

**Solution:**

This is fun way to learn number theory or some Math. So, go ahead and try it. Your suggestions, answers, comments are welcome 🙂

More later,

Nalin Pithwa

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## 2 Comments

Somebody asked me this once…. I was waiting to see if anybody else would reply but since nobody did, the answer is 142857.

good