The Weekly Warlock Wind-Up: It’s a sign! (answer)

This week, I posed to you this question and this sequence of numbers:

“Assume you’re using a basic calculator and you press the numbers in the order shown, replacing each question mark with a mathematical sign. Add, subtract, multiply and divide can each be used only once. What’s the highest number you can possibly get?”

5 ? 4 ? 7 ? 3 ? 2

After the break we’ll take a look at the answer, so click on through!

The key to working this one out is simply logic – you’re aiming for the highest number possible, so everything you do needs to make the end result bigger.

Let’s ignore the order of the sequence for now and look at the numbers and signs: 2, 3, 4, 5, 7 and then +, -, * and /.

To make the biggest number possible, we obviously need to multiply by the largest number. So, *7.

We need to divide by the smallest number, so /2.

We have addition and subtraction left – we add the remaining biggest number and subtract the remaining smallest: +4 and -3 (we can’t use 5 because it’s at the start of the sequence).

Therefore, filling in the blanks, we have 5 + 4 * 7 – 3 / 2 = 30.

So how did you do?

Vel.

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6 Responses to “The Weekly Warlock Wind-Up: It’s a sign! (answer)”

  1. Tom Says:

    That one was too easy, slacker 😛

  2. Koch (Aszune) Says:

    Not that I don’t agree about multiplying by the largest, adding the second largest etc etc, but..

    5 + (4*7) – (3/2) would be the order of calculating this, wouldn’t it? 5 + 28 – 1.5 = 31.5.

    *runs back to smart-alec corner*

    • Veliaf Says:

      Hi Koch,

      I see what you’re getting at with the order of operations, but if you really were using a physical calculator to do this then you would have to work everything out as you went along, rather than using brackets.

      If you came across 5 + 4 * 7 – 3 / 2 written down on a page then doing it your way would be correct, but you wouldn’t actually see that if you used a calculator.

      If that makes sense 😀

      • Koch (Aszune) Says:

        And here I was just about to post a lengthy reply about proper calculators accepting lines of text and all… before I actually read the orinial post:

        “Assume you’re using a basic calculator”

        *grumbles* I seems your kung-fu math is superiour to mine, old man.

      • Veliaf Says:

        Every time, my young padawan 😉


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