This is an indirect way of asking your age and telling the same to you. This is simple arithmetic to fool the people. Let's get into detail.
The difference between 1754 and 2004 (current year) is 250. This difference is achieved by adding 5 and multiplying the same by 50, which comes out to 250. Indirectly we will arrive at the current year and subtracting our birth year will give our age.
Then what happens to the initial number (between 1 to 10) that we have chosen. That number will be safely kept at the third digit at the end of the calculation. This is because that number is initial multiplied by 2 and then multiplied by 50, which means it is actually multiplied by 100.
This will work only for two digit ages only. If we try for three digit age, then this problem will give wrong answer.
And one more thing, this problem will work for any year. The only change we have to make is to increase the number 1754 by one, every year.