Find the volume of a rectangular parallelepiped if its three dimensions are equal to 6 1 / 4dm, 2 2 / 5dm, 1 4/5 dm.

We can find the volume of a rectangular parallelepiped by multiplying its three dimensions. But for the convenience of the calculation, you need to convert the measurement values to the form of an incorrect fraction. To do this, multiply the whole part by the denominator of the fraction and add the numerator:
6 1/4 = (6 * 4 + 1) / 4 = 25/4 dm
2 2/5 = (2 * 5 + 2) / 5 = 12/5 dm
1 4/5 = (1 * 5 + 4) / 5 = 9/5 dm
Now we multiply these values and find the volume:
25/4 * 12/5 * 9/5 = 2700/100 = 27 dm3
Answer: the volume of the parallelepiped is 27 dm3.