1 and 2/3 or 1 2/3 expressed as a decimal is, 1.666667. How I got this answer is:
1 2/3 is a mixed fraction, so what I do to convert that into an improper fraction(the numerator is a higher number than the denominator or equal to the denominator) is I multiply the whole number, 1, by the denominator and the add the numerator so, 1 * 2 = 2. Then, 2 + 3 which equals 5. Also, the denominator stays the same so the improper fraction would be, 5/3. To convert an improper fraction to a decimal you just divide the numerator by the denominator. Therefore, the answer is 1.666667!