To convert the mixed number 1 7/8 into an improper fraction, you start by taking the whole number part and multiplying it by the denominator of the fraction part. In this case, the whole number is 1 and the denominator is 8.
So, you multiply:
1 x 8 = 8
Next, you add this result to the numerator of the fractional part:
8 + 7 = 15
Now you place this result over the original denominator to form the improper fraction:
15/8
Therefore, the mixed number 1 7/8 can be expressed as the improper fraction 15/8.