A bag of potatoes weighs 9.42 pounds on a weighing scale.
In order to find least significant digit we have these rules,
1. The leftmost non zero digit is the most significant digit.
2. If there is no decimal point, the rightmost non zero digit is the least significant digit.
3. If there is a decimal point, the rightmost digits is the least significant digit even if it is a zero.
4. All digits between the least and most are also significant digits.
In our case rule number 3 is to be applied.
Our number is 9.42, the rightmost digits that is 2 is the least significant digits.