Because what your doing is breaking apart the dividend to make it easy to divide with the divisor.
Example 189/3
What you do is place value in hundreds would be
180/3= 60
9/3=3 add together you get 63
168 divided by 4 equals 42 words per minute
3 to the 1st is 3
3 to the 2nd is 9
3 to the 3rd is 27
3 to the 4th is 81
3 to the 5th is 243
3 to the 6th is 729
<em>I hope this helped!!</em>
The unit rate of 521 miles in 14 hours is 37.214 miles per hour.
