 Mind Bender #3 : Solution

Last month, a couple of people suggested that I needed to “raise the bar” a little. And, judging from the handful of responses that came back … it seems this Mind Bender may have slowed few of them down.

In fact, I think there were actually only three of you, who managed to finally work it out.

Here is the solution you needed …

table{width:350px;margin:0 auto;}.
|{width:100px}. *1 = 77/77*|{width:100px}. *11 = 7/.7 + 7/7*|
|*2 = 7/7 + 7/7*|*12 = (77+7)/7*|
|*3 = (7+7+7)/7*| *13 = (7+7) – 7/7*|
|*4 = 77/7 – 7*|*14 = (7+7) x 7/7*|
|*5 = 7 – (7+7)/7*|*15 = (7+7) + 7/7*|
|*6 = [(7 x 7) – 7]/7*|*16 = [(7 -.7)/.7] + 7*|
|*7 = 7 + [(7-7)/7]*|*17 = [(7 x .7) + 7]/.7*|
|*8 = [(7 x 7) + 7]/7*|*18 = 77/7 + 7*|
|*9 = 7 + [(7+7)/7]*|*19 = (7+7 -.7)/.7*|
|*10 = 77/7.7*|*20 = 7/.7 + 7/.7*|

So, in fact, you can actually create every number between 1 and 20 using only four 7s.

As you’ll appreciate, there are many variations on how these can be arrived at. In fact, one client (who worked all of them out) also sent me a program giving literally hundreds of different combinations.

However, mine are perhaps a little more straight forward. And, as I said when we embarked upon these Mind Benders – there can often be a certain elegance in simplicity.

Until next month …