MULTIPLYING BY 1/2 is really nothing more than cutting a number in half. Now sometimes that is an easy thing to do, like 1/2 x 4 = 2, because half of four is two.
Other times it is not quite so easy to cut a number in half, like 1/2 x 735 = ?
Here we will show you some quick and elegant ways to cut in half in your mind.
Here take a look :
Now you try a few. Click on the question mark to see if you are correct.
So it looks like we need to mentally halve two EASY parts instead of one hard part.
(6 + 1)(1/2) means half of six PLUS half of one, or 3+.5=3.5.
Let's try 9:
Nine = 8 + 1, so we just cut those each in half and put the halves together. Half of eight PLUS half of one is 4+.5=4.5.
What about 90?
That IS an even number because it ends in zero, but it has an ODD digit in it, and therefore it makes our brains slow down a bit when cutting it in half.
Have no fear! This trick works for numbers ending in zeros too.
Think of 90 as (80 + 10). Halve each of those easy numbers and put your results together. Half of eighty PLUS half of ten is 40+5=45.
How about 7,000?
Same idea here. Change the 7,000 to (6,000 + 1,000) and take half of each of those. Half of 6,000 PLUS half of 1,000 is 3,000+500=3,500
Often you will have a mixture of ODD and EVEN digits in a number. Just remember the trick of breaking it up into easy parts, and you will be fine.
Let's take a look at a few examples. We will make them harder as we go. Then we will give you a chance to practice before the password clues are given.
YOU TRY THESE:
If you got those right, you are ready to try to find the password to the treasure room. Just follow the directions below.
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