To compare the numbers 123,893, 31,892, and 12,786 using scientific notation, we first convert each number as follows:
-
123,893 can be written in scientific notation as: \[ 1.23893 \times 10^5 \]
-
31,892 can be written in scientific notation as: \[ 3.1892 \times 10^4 \]
-
12,786 can be written in scientific notation as: \[ 1.2786 \times 10^4 \]
Now we can compare the exponents to determine the least value:
- The first number \(1.23893 \times 10^5\) has an exponent of \(5\).
- The second number \(3.1892 \times 10^4\) has an exponent of \(4\).
- The third number \(1.2786 \times 10^4\) also has an exponent of \(4\).
Since \(10^5\) is greater than \(10^4\), both \(31,892\) and \(12,786\) (which have an exponent of \(4\)) are less than \(123,893\).
Next, we compare \(3.1892 \times 10^4\) and \(1.2786 \times 10^4\):
- \(3.1892 < 1.2786\)
Thus, \(1.2786 \times 10^4\) (which corresponds to \(12,786\)) is the smallest.
So, the number with the least value among them is:
\[ \boxed{1.2786 \times 10^4} \]