Ken is a factory worker, who is a part-time statistics student, and makes toys. He knows that the probability that any given toy on the factory line is faulty is a constant and is independent of whether or not any other toy on the line is faulty. This probability is 0.0906 (when rounded to 4 decimal places). Each day, Ken tests the same number of toys. He knows that the expected number of faulty toys each day is 31.

Given this information, calculate the number of toys that Ken tests each day. Give your answer as a whole number.

Number of toys Ken tests each day =