Math on Time


I found Ian’s watch a couple days ago, buried in a drawer I was organizing. He happily strapped it on his wrist and set about determining the time. We have worked on time-telling a little bit here and there, so we reviewed the “math” of each hand.

Today, he demonstrated a math trick that, seriously, I’ve never thought of doing for a clock. But that’s not saying much – I did well in math, but had a weak foundation of math reasoning. Anyway, here’s how the forehead-slapper went:

Ian: It’s 10:50
Me: You’re right! I’m impressed that you figured out “50” so quickly.
Ian: Well, I knew that 10 was in a place next to 100 and half of 100 is 50.
Me: Well, huh. That’s exactly right.

So, yeah, where as I spent my life skip-counting fives around the clock until I knew the multiplication, my 7-year-old simply adds a zero and halves it. Now, I want to know if I’m the  last one to hear of this fancy math stuff.

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