Answer:
Reduction
Step-by-step explanation:
Omg I have the same page as you. But here’s the first one for number 19
139852
one hundred thirty nine thousands eight hundred fifty two
Answer:
a difference of squares
Step-by-step explanation:
Let's write down the expression:

we can see that this expression is one of the form
which is the general expression of a difference of squares.
To be more specific and to see why we say this, let's make
and 
Now, if we substitute this in the general formula, we get:

Thus, this expression is a difference of squares.
10 times 147 equals 1470
10 x 147 = 1470