Math with the Clock

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The main issue in these problems is that students have to deal with 3 different number bases – Decimal, twelve &amp; sixty.

Let us take an example. Ram starts his weekly run at 3:24:45 p.m and ends his run at 6:12:37 p.m. How long did he run?

Actually it is a simple subtraction problem of 6:12:37 – 3:24:45. What makes it complicated is the different number bases used in every stage.

The seconds, 45 and 37 have a base of 60, because 60 seconds make a minute! Since 37 is less than 45, we rewrite the problem as

6:11: 97 – 3:24:45 writing 12.37 as 11:97 (37 seconds past 12 is the same as 97 seconds past 11! The concept is similar to &ldquo;borrowing&rdquo; while subtracting.

Again in the minutes section, 11 is smaller than 24. So we again rewrite as

5:71:97 – 3:24:45 which now can be written as 2:47:52.

So it is a simple subtraction problem made complicated by the different bases for minutes &amp; seconds. This can be very confusing for primary school students.

It is best to do these problems in middle school.

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