DAY/DYDD/GIORNO/NAP 180:

T he Main Challenge

This is a continuation of a number puzzle, posted on DAY 10, made famous by French writer, George Perec.

In that challenge, we asked you to use seven 7’s (7, 7, 7, 7, 7, 7 and 7) once each, with + – × and ÷ available, to make target numbers from 1 to 3.

To continue the puzzle, and make 4, you could simply do:

We now invite you to make all the target numbers from 5 through to 9.

The 7puzzle Challenge

The playing board of the 7puzzle game is a 7-by-7 grid of 49 different numbers, ranging from 2 up to 84.

The 1st & 6th rows contain the following fourteen numbers:

2 5 9 12 14 15 18 20 22 33 40 49 56 72

Which multiple of 8, when 7 is subtracted from it, becomes a square number?

The Lagrange Challenge

Lagrange’s Four-Square Theorem states that every integer can be made by adding up to four square numbers.

For example, 7 can be made by 2²+1²+1²+1² (or 4+1+1+1).

Show how you can make 180, in TEN different ways, when using Lagrange’s Theorem.

The Mathematically Possible Challenge

Using 3, 6 and 12 once each, with + – × ÷ available, which is the ONLY target number it is possible to make from the list below?

8 16 24 32 40 48 56 64 72 80

#8TimesTable

The Target Challenge

Can you arrive at 180 by inserting 4, 6, 8 and 10 into the gaps on each line?

Answers can be found here.

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