Any whole number can be written as a fraction. All we do is place the number over 1.
For example, the whole number 7 is the same as the fraction 7/1.
If we wanted to multiply the whole number 7 with the fraction 2/3 then...
In the jump from the second step to the third step, we multiply straight across. The numerators multiply together. The denominators multiply together. The fraction 14/3 cannot be reduced because 14 and 3 don't have any factors in common other than 1.