Lesson: Multiplying by Doubling and Halving.

Comment on Multiplying by Doubling and Halving.

Tabish Badar's picture

What a classic strategy!
greenlight-admin's picture

Thanks - glad you like it!

Wow!! impressive

Extremely useful technique. This is my first time hearing about this. Thanks Brent!

Excellent technique, will come in handy while dealing with small number.

They will never teach you this in Kap, Man-P, and Prince. Just saying. I was fortunate to pay for those super expensive courses both online and live. There are several ways to skin a cat and boy was I learning to skin the cat the wrong way all this time. It was always quantity oppose to quality for those super expensive bureaucratic test prepping models. Thank you Greenlight Test Prep and Brent for differentiating profoundly from your competitors.
greenlight-admin's picture

Thanks for taking the time to say such nice things! It made my day!


Brent, you are absolutely welcome my friend.

This technique only works for even numbers?
greenlight-admin's picture

Good question.

The technique works for all numbers, but it doesn't always make calculations easier.

For example, the product of 19 x 11 EQUALS the product of 38 x 5.5, but the second product isn't necessarily easier to calculate.

Conversely, the product of 18 x 4 EQUALS the product of 9 x 8. In this case the second product is probably easier to calculate.

As I mention in the video, the technique works really well when one value ends in 5.
For example, the product of 35 x 18 EQUALS the product of 70 x 9, and the second product is easier to calculate.


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