Question

which number produces an irrational number when multiple by 1/3

Answer 1

ny irrational number will remain irrational when multiplied by a rational number. 

For example: 
π * 1/3 = π/3 
√2 * 1/3 = (√2)/3 


Answer: 
Any irrational number (e.g. π, √2, √3, etc