Numbers Bigger Than 12

Date: 03/22/97 at 20:09:33
From: alice flanders
Subject: Multiplication of Numbers Bigger Than 12

Dr. Math,

How do you do a hard multiplication problem like 14x7?

Date: 03/23/97 at 03:12:27
From: Doctor Mike
Subject: Re: Multiplication of Numbers Bigger Than 12

Dear Alice,
  
In such a situation I would break this hard problem up into two 
easier problems.  Since 14 sevens is the same as 10 sevens plus
4 more sevens, it makes sense to do those two problems first, and
then add up those two answers to get the grand total answer : 
  
   How much is 10 sevens ?  ................  70
   How much is  4 sevens ?  ................  28
                                             ----
   Add them up to find 14 sevens  ..........  98 
  
I hope this helps.  When your class gets to learning about ways
to do multiplication of these larger numbers, be sure to remember
that the 1 in 14 really means "ten".  That's important to know. 

-Doctor Mike,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/