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David Njoku
davidnjoku@mastodon.world
Edited 28 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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