Multiplication assignment 3:

1. Find the product of 486 × 39

a. Using the expanded algorithm for multiplication

b. Using lattice multiplication

c. Using the standard algorithm for multiplication.

2. In the standard algorithm for multiplication, when multiplying:

486
×39

one of the things you do in the problem is to multiply 3 tens by 6, which gives you 24 tens = 240.  When you write that down, you put 4 in the tens place (because it's 4 tens), but when you carry the 2 you put it above the tens place instead of above the hundreds place.  Write your best explanation for why you do that, and why it makes sense. (I'm looking for something beyond just the rule says to put it there).

3. a. Give an example of how knowing the commutative law helps children learn the multiplication facts.

b. Give an example of how you could use the distributive law to figure out a multiplication fact by using easier multiplication facts.