How to Add (Week 5, Day 1)

So you’ve found yourself in the ancient world, no paper or pens in sight, and you need to add some three digit numbers together. Lets so say that you’ve been hit on the head and you have no memory of the Hindi numeral system and only know… say… Roman numerals. How do you do it? Start by picking up some pebbles.

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First pile up the stones according to place values.

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Okay. Now we are ready to begin.

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Take all the pebbles in the units column and put them together.

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If there is more than ten move one pebble to the tens column and discard nine more.

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Then do the same thing for the tens column. Bring all the pebbles together.

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If there is more than ten, carry the one pebble, and discard nine.

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Continue until there are no more pebbles to be added.

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You have now reached your result.

So you have just shown that CLVII + CDXCVI = DCLIII.

By the way, if you type an expression in Roman numerals into Google, it will give you the answer in Roman numerals. I just discovered that.

Now you know how to add like an ancient. Way to go!

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