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David Njoku
davidnjoku@mastodon.world
Edited 4 days ago
Here's some interesting maths homework that my son got.
Using only four 4s and whichever operators you choose, come up with sums that equal every number from 1 to 20.
For example, 16 is 4 + 4 + 4 + 4. And 2 is (4/4) + (4/4).
5 is (√4 x √4) + 1. And 8 is 4 + 4 + 4 - 4.
We've got answers for most of them, but are struggling with a few. Haven't got his book in front of me now, but I think we don't have an answer for 10, for example.
PS: You must use all 4 fours.
EDIT: 5 is (√4 x √4) + (4/4)
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@davidnjoku Ø[4,4,4,4]
Where the Ø[…] operator is one that I’ve just invented
Now, what was the target result you wanted, again? :)
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Palmer Dabbelt
palmer
for 11 and 13 I'm assuming "square" is an operator, not sure if that's allowed?
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1 = 4/4 * 4/4
2 = 4/4 + 4/4
3 = 4/sqrt(4) + 4/4
4 = 4 + 4 - sqrt(4)*sqrt(4)
5 = sqrt(4)*sqrt(4) + 4/4
6 = 4 + 4 - 4/sqrt(4)
7 = 4 + 4 - 4/4
8 = (4 + 4) * (4/4)
9 = 4 + 4 + 4/4
10 = 4*sqrt(4) + 4/sqrt(4)
11 = sqrt(((4! - 4/sqrt(4))^2)/4)
12 = 4*4 - sqrt(4)*sqrt(4)
13 = sqrt(((4! + 4/sqrt(4))^2)/4)
14 = 4*4 - 4/sqrt(4)
15 = 4*4 - 4/4
16 = 4*4 * (4/4)
17 = 4*4 + 4/4
18 = 4*4 + 4*sqrt(4)
19 = 4! - 4 - 4/4
20 = 4*4 + sqrt(4)*sqrt(4)
2 = 4/4 + 4/4
3 = 4/sqrt(4) + 4/4
4 = 4 + 4 - sqrt(4)*sqrt(4)
5 = sqrt(4)*sqrt(4) + 4/4
6 = 4 + 4 - 4/sqrt(4)
7 = 4 + 4 - 4/4
8 = (4 + 4) * (4/4)
9 = 4 + 4 + 4/4
10 = 4*sqrt(4) + 4/sqrt(4)
11 = sqrt(((4! - 4/sqrt(4))^2)/4)
12 = 4*4 - sqrt(4)*sqrt(4)
13 = sqrt(((4! + 4/sqrt(4))^2)/4)
14 = 4*4 - 4/sqrt(4)
15 = 4*4 - 4/4
16 = 4*4 * (4/4)
17 = 4*4 + 4/4
18 = 4*4 + 4*sqrt(4)
19 = 4! - 4 - 4/4
20 = 4*4 + sqrt(4)*sqrt(4)
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