4.8.5 Human Calculator
Now, let’s look at a quick way to attack division by nine.
Activity: The Human Calculator Watch this short video to discover the power of your brain:
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see it in standard view
Now see how quickly you can perform these
calculations in your head.
2154 division nine Hint
Write down the first number of the dividend, then use
addition. Watch out for carries!
multiline equation line 1 two one five four prefix division of nine line 2 two three eight super one 12 cubed line 3 two three nine cap r times three
. 2154 division nine equals 239 cap r times three
three one zero two one two prefix division of nine Answer
multiline equation line 1 three one zero two one two prefix division of nine line 2 three four four six seven super one nine super zero line 3 three four four six eight
. three one zero two one two prefix division of nine equals 34 comma 468
(This one is tough—you might need to
write the shortcut out!) three two six four four one two division nine Answer multiline equation line 1 three two six four four one two prefix division of nine line 2 three five super one one super one five super one nine squared zero times super two 22 super four line 3 three six two six super one one two cap r times four line 4 three six two seven one two cap r times four
. three two six four four one equation left hand side two division nine equals right hand side 362 comma 712 cap r times four
Aren’t you impressed by the power of your brain? You should be! Of
course, the real math is understanding why this trick works, but you’ll have
to study much more math to find that out.
Now you have finished the optional activities as well it is time to
move onto Unit 5 [Tip: hold Ctrl and click a link to open it in a new tab. ( Hide tip) ] and continue to work with numbers. To be precise, you will work with various units of measurement and negative numbers. See you there and keep going!