Step 1: Identify the base-3 number, which is '2101'.
Step 2: Write down the place values for each digit in '2101' from right to left: 3^0, 3^1, 3^2, 3^3.
Step 3: Assign the digits to their respective place values: 2 is in the 3^3 place, 1 is in the 3^2 place, 0 is in the 3^1 place, and 1 is in the 3^0 place.
Step 4: Calculate the value of each digit multiplied by its place value: 2 * 3^3 = 2 * 27 = 54, 1 * 3^2 = 1 * 9 = 9, 0 * 3^1 = 0 * 3 = 0, 1 * 3^0 = 1 * 1 = 1.
Step 5: Add all the values together: 54 + 9 + 0 + 1 = 64.
Step 6: The decimal equivalent of the base-3 number '2101' is 64.
