146. From a natural number, the sum of its digits was subtracted, and then one digit was erased from the resulting difference. The sum of the remaining digits of the difference is 131. Which digit was erased?
$\triangle$ The difference between a natural number and the sum of its digits is divisible by 9 (see problem 130). Let the erased digit be denoted by $x$. Then the sum $131+x$ is divisible by 9, from which $x=4$.

Answer: 4