What’s 19,000 – 10,000 ?


Here’s another one: what’s 50 times 0.5?

If you were able to answer these questions without having to resort to using a calculator, then my guess is that you are most likely over 45 years old. If you are less than 30, my guess is that you opened up the calculator app on your smartphone in order to find the answer.

Over my 29 years of teaching, it seems to me that more and more college students either can’t do basic math calculations in their head or don’t have the confidence to trust such an approach. The result, either way, is an over-reliance on a calculator.

And I know my students are bright, as evidenced by strong SAT scores (both math and verbal) and stellar high school transcripts.

So I’m not sure if I should be concerned or not.

It seems like everyone has a smartphone these days, at least everyone under 30), and a calculator is a basic app on all smartphones. So if that’s the case, do they really need to know how to do basic math calculations in their head?

Perhaps it’s my age showing, but I still think it’s important to be able to do basic math problems either in your head or with just a paper and pencil. If nothing else, it allows you to verify the answer that the calculator has given you.

I am certainly not anti-calculator; in fact I downloaded and frequently use an amazing financial calculator app for my iPhone that emulates the TI BA II Plus Professional, allowing me to do all sorts of financial calculations such as present value, future value, NPV, etc. (It’s one of the few apps I’ve ever paid for.)

I no longer do such calculations by hand, so I see the value in using such tools.

But at what point do such tools become a crutch, or actually start to eat away at the knowledge you once had of how to solve a problem by hand.

I realize people have different strengths. So while perhaps one of my strengths is math, my students have shown great strengths in areas such as writing, singing, playing basketball, critical thinking, leadership, or empathy.

So I guess at the end of the day, if someone needs to use a calculator to solve (19,0000 – 10,000), as long as they get the right answer, I guess I should be OK with that. (Would Dan Pink call this an example of a ROWE – Results Only Work Environment?)

But it still probably won’t stop me from wanting to scream the answer out while students are busy typing such problems into their smartphone.

By the way, (19,0000 – 10,000) equals 9,000 and 50 times 0.5 is 25.

And not to brag, but I didn’t even use a calculator.

P.S. Don’t get me started on spelling…

3 thoughts on “What’s 19,000 – 10,000 ?

  1. Actually, there is a body of research that suggests that not knowing basic math facts and math relationships hinders problem solving. The brain can handle about 5 pieces of information in working memory at a time. If the math facts that support a problem are known to automatically, the brain handles this information naturally and it is not considered one of the five pieces in working memory. This allows other information relative to the problem to be handled by working memory. There are also studies that show that nations who are consistently ranked with the top performing students in math use calculators in math classes far less than we do in the US. They are much more “fluent in math” and as a result are better problem solvers.


    1. Hi Daryl,

      It’s great to hear from you and thanks for your insights on the issue. The research seems to make sense. How does your school treat the use of calculators?



      1. Quincy

        Sorry it took so long to get back to you. In my opinion we use them too much. Recently, we have backed off in the elementary schools and there is more focus on learning math facts etc. But in middle and high school their use is widespread. The graphing calculators do too much but there is not interest on the part of the math department to examine their use and acknowledge that while they have many advantages— their indiscriminate use negatively impacts problem solving, number sense and algebra skills.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.