Thursday, September 15, 2011

Split It

Split It

This is an easy strategy to split a number like 7,758 in half.

What I look for is a way to make splitting the number easy by using simple mental calculations. Usually, the first step is to decompose the number into its place values. So, 7,758 becomes

7,000 + 700 + 50 + 8 .

Then, I ask that a student rewrite any number that they cannot readily split. Usually, these numbers start with odd numbers. We'll look at 7,000.

7,000 could be rewritten as 6,000 +1,000 (both of which are easy to split).

After that, it's all down hill.

The whole number could be rewritten as
6,000 + 1,000 + 600 +100 + 40 + 10 +8,

and finding half of these numbers should be EZ!
3,000 +500 +300 + 50 +20 +5 +4 = 3,879!

Try it!!