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Advent calendar 2018
18 December
All 2018 advent puzzles
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There are 6 terms in the expansion of \((x+y+z)^2\):
$$(x+y+z)^2=x^2+y^2+z^2+2xy+2yz+2xz$$
Today's number is number of terms in the expansion of \((x+y+z)^{16}\).
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153
In general, the expansion of \((x+y+z)^n\) will have \(\frac12n(n-1)\) terms.
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number
scales
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dominos
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averages
balancing
folding tube maps
chess
determinants
time
triangle numbers
geometry
bases
integers
clocks
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algebra
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multiplication
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ellipses
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spheres
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