Rational Number and Integer | PRMO 2019

Content

Try this beautiful problem from the PRMO, 2019 based on Rational Number and Integer.

Rational Number and Integer – PRMO 2019

let the rational number \(\frac{p}{q}\) be closest to but not equal to \(\frac{22}{7}\) among all rational numbers with denominator < 100, find p-3q.

Rational number

Algebra

Integer

But try the problem first…

Answer: is 14.

Source

First hint

|\(\frac{22}{7}-\frac{p}{q}\)|=|\(\frac{22q-7p}{7q}\)| then |22q-7p|=1 for smallest value

Second Hint

and q=99 then p=311

Final Step

p-3q=311-(3)(99)=311-297=14.