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#### 解开大猫军队谜题

Can you solve the giant cat army riddle? - Dan Finkel

.

The villainous Dr. Schrödingerhas developed a growth ray

and intends to create an army of giant cats

to terrorize the city.

Your team of secret agents has tracked him to his underground lab.

You burst in to find…

that it’s a trap!

Dr. Schrödinger has slipped

into the next room to activate his device

and disabled the controlpanel on the way out.

Fortunately, your teammates are masters of spy-craft.

Agent Delta has hackedinto the control panel

and managed to reactivatesome of its functionality.

Meanwhile, agent Epsilon hassearched through surveillance

to find the code for the door:
2 10 14
2, 10, 14.

All you have to do is enter those

numbers and you ’ ll be free.

But there’s a problem.

The control panel has only three buttons:

one which adds 5 to the display number,

one which adds 7, and one which takes the square root.

You need to make the display output the numbers

2, 10, and 14, in that order.

It’s okay if it outputs differentnumbers in between,

but there’s no way to reset the display,

so once you get to 2,

you ’ ll have to continue on to 10 and 14 from there.

Not only that, Agent Delta explains

that there are other trapsbuilt into the panel.

If it ever shows the same numbermore than once,

a number greater than 60, or a non-whole number,

the room will explode.

Right now, the display reads zero,and time is running out.

There ’ s only one way to solve the puzzle,

with a few small variations.

How will you input the code to escape

from Dr. Schrödinger ’ s lair

and save the day?

Pause the video now if you want to figure it out for yourself!

3
3
2
2
1
1

+5或+7会增大数字
Adding 5 or 7 increases the number,

and the square root buttonwill make it smaller.

But there are only a few options where you can use that button:
4 9 16 25 36 和49
4 9 16 25, 36, and 49.

You’d love to make 4 or 16.

Then you could hit the square root button once or twice to get 2.

But you can ’ t make either with just the 5 and 7 buttons.

What will you do?

You look at the other possible options

for numbers you could take the square root of.
9 开方得不到2
Nine you can’t reach.
25和49开方会返回到5或7
Twenty-five and 49 would take you back to5 or 7,
5和7是你本来就拥有的数字
and you can already get to eachof those.
36就是你的唯一选择

You add 5, 7, 5, 7, 5, 7,

and then hit the square root button.

Why that series of 5s and 7s?

It’s somewhat arbitrary,

but you know that you want to avoid 10, 14,

and perfect squares,

since you’ll need them later.

This gets you to 6.

Does that help?

Looking at your options, you see that 16 is now in your sights.

You add 5 twice more to reach it.

Then hit square root twice.

That gets you to 2.

Now to 10.

You can’t get straightthere through addition alone,

so you’re going to haveto reach another square.

Taking the square root of 9 or 25 would get you to a good place,

but it turns out that 25is unreachable from 2.

So you add 7 to get to 9,

then take the square root again.

That gets you to 3.

Finally, you need to reach 14.

Thinking backwards, you imagine where you could be before 14:

7 or 9.

But 9 won’t work becauseyou’ve already used 9.

However, you could get to 7by reaching 49 first.

being careful not to hit any

of the numbers you ’ ve hit so far.

square root to 7, and add 7 more.

The door opens,and you’re out of the trap.

your team gets Schrödinger ’ s cats out

of the box in the nick of time.

As for Schrödinger,you can be certain of one thing:

he ’ ll be spending quite some time in a box of his own.

Interested in navigating another amazed numbers?

Try this one now.

You need to get from 11 to 25,

and the only operations available are
×2或－3
multiplying by 2 or subtracting 3

What’s the fewest number of moves that’s possible in?

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