Published on Nov 19, 2015

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FIND THE PRODUCT

Multiplication can be thought of as repeated addition.

In this problem, you might think of 18 groups of 14 being added together one at a time.

In this problem, you might think of 18 groups of 14 being added together one at a time.

Photo by liquidnight

18 GROUPS OF 14

I bet she's thinking about using that calculator.

Even if she decides to use her calculator, she'll have to keep up with each addition so that she performs exactly 18 of them.

Photo by Steven Leith

NO CALCULATOR

NO CALCULATORS!!!

Does this mean that we'll have to keep adding 14 until we've added all 18 addends?

By the way, I've forgotten why we are multiplying 18 times 14. We'll get back to that later.

Photo by Bilal Lashari

NOT!

Even with the calculator, we'd have to be sure to enter 14 exactly 18 times.

Photo by angelsk

Let's gather larger groups of 14 together so we don't have to perform so many additions.

Let's CHUNK!

Photo by Leo Reynolds

THAT'S 140

I like 10 because it is a friendly number to add, subtract, multiply, or divide by.

Let's add 10 chunks of 14 together.

Let's add 10 chunks of 14 together.

Photo by onezilla

THAT'S 70 MORE (140+70+?)

Five is another friendly number in multiplication. I know my multiples of five.

And five is half of ten.

And five is half of ten.

Photo by Leo Reynolds

THAT'S 28 MORE (140+70+28+?)

Those twos are also friendly numbers. Multiplying by two is the same as doubling a number.

Photo by Leo Reynolds

THE PRODUCT IS 252.

We're done! Did anybody do this a different way?

Photo by Sean MacEntee