Word Problems and Multiplication

When you come across a word problem that has any of these words – product, times, twice, or of, chances are you’re going to have to multiply.

Now, this is not a comprehensive list of all of the words that would tell you to multiply, but this is a few of them.


The transcript is provided for your convenience
Let’s look at an example. If Maryann opens a bank account with $450 and earns 12% interest each month, what will her total balance be at the end of the first month?

So, what they’re asking us to find is our total balance. Since I don’t know the total balance, then I’m going to have to use a variable for that. So, let’s say t then is going to be our total balance.

And, in order to find my total balance, I’m going to have to take what she’s starting out with, her $450, and the amount that she earns interest in that month. So, my total balance will be found by taking the starting value and adding the interest, to find my total balance.

So, to find my total balance, I’m going to have to know the starting value. So, we’ll use an s for starting value, which is $450, and I also have to know my interest, so we’ll use i for interest. And, interest is going to be found by doing 12% of the amount of money she has in her account. So, we’re going to do 12% of $450.

Okay. So, to find our total balance, we’re going to have to take our starting value and add our interest to that, and our starting value is $450, so our total balance is going to be $450 plus our interest, and our interest we said was 12% of $450, and there’s one of those words that means multiplication.

So, in order to find our interest, we’re going to have to do 12% times 450. But first, we’re going to change our percent to a decimal. So, we move our decimal two places to the left, so we get 0.12 times 450 as our interest, and 0.12 times 450 is 54. So, our amount of interest that we earned in that month was $54. Therefore, our total amount is $450 plus $54. And then we just add two amounts together. Therefore, our total amount is $504, and that’s how much money we have after one month.


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