The Comma Method for Reading Large Numbers

Once I developed this tip, my students quickly mastered how to read long numbers.

Take the example 165,247,873

I showed my students that within each comma, the numbers follow the standard hundreds-tens-ones protocol. The comma simply indicates whether you are dealing with millions, thousands or plain old units (the name some people give the hundreds-tens-ones group.)

Each three-digit group can be read as if it were just a hundred. Referring to our example number, you first say “One hundred sixty-five.” The comma signifies millions since you are in the third comma group from the right. Thus, you begin reading the number by saying “one hundred sixty-five MILLION.” (Capital letters added for emphasis—they’re very helpful for students.)

Then, you read the next three-digit group as if it were a hundred: “two hundred forty-seven” and then add the THOUSAND. (I point to the comma as I loudly say “THOUSAND.”

Last, read the last three-digit group as a regular number: “eight hundred seventy-three.”

Thus, your number is “one hundred sixty-five MILLION, two hundred forty-seven THOUSAND, eight hundred seventy-three.”

Once I taught my students this, they understood why each place is important. They had less trouble reading and writing numbers with a zero as a placeholder, such as 207,800. After all, you just read each three-digit group as a regular old hundred: “two hundred seven THOUSAND, eight hundred.”

Ironically, our math book teaches place value only to the ten thousands. I think that’s to save children from that horrifying extra place value that would take them to the hundred thousands. But when I taught to the hundred thousands and even hundred millions using this method, the confusion (for the most part) went away.

Comments Off on The Comma Method for Reading Large Numbers
Posted in Academics,Math by Corey Green @ Nov 29, 2011

 

No Comments

No comments yet.

RSS feed for comments on this post.

Sorry, the comment form is closed at this time.