Aops guy explains quite clearly
2009 is his earliest year, 2009 2010 2011 2014 2015 2016 2017 2018 2019done
divided by year - he skipped the 2 hardest problems of 2019.
https://artofproblemsolving.com/videos/mathcounts
2013 v37 s2 target 3 wilma??
v38 team 5
v39 s9 team 10
v40 s4
https://www.mathcounts.org/sites/default/files/u1706/MinisAlgebraDec2013.pdf
v41 s11 s30
v42 s14 s22 team 2
v43 s17 s24
v45 s29 2013 inscribed rectangle inside a triangle has max area as half of triangle
2014
v46 s9 s8
v47 s12 t3
v48 s17 s22 t7
v49 s20 s24 s29
v50 s18 team 7
v51 s21 team 9
v52 team 4 repeat!!! s30
v53 s15 s27
v54 s23 team 10
2010
v10 s27 28
v11 team 10, target 8
v12 s17, 29
v13 target 2
v14 s20, team 4
v15 team 9
v16 team 8
v17 s13 team 5 s15
v18 s16 s18 target 6
2011
v19 team 1 s21 team6
v20 first 2 unknown; s30 square difference formula
v21 s10, counting parallograms
v22 s16 s17 team 8
v23 s15 target 6 s24
v24 octahedron? team 5
v25 s22, s26, team 10
v26 s29 team 9
v27 s28 target 8
2015
v55 s7 s8 s25
v56 s11 team 5
v57 s14 s20 target 3
v58 s16 s24
v59 s17 s22
v60 s26 s15
v61 s12 s23 target 4
v62 team 2 many circles, s30
v63 target 6, t8
2018
v82 s6 s24
v83 s10 s13
v84 target 4, s11 - clever idea - rotate the line to make trapezoid area equal to a rectangle area!
v85 s19 forward path counting/backward also works! just don't use complementary counting!
v86 s14
v87 s25
v88 s29 team 7
v89 target 8 s26
v90 s 21 target 6
2019
v91 s10 s13 s14
v92 s21 s24
v93 s5 s16
v94 s15 s22
v95 target 6
2009 2016 2017 done
2017 73 s8, 10
74 11 25
75 23 team 1
76 t2 team 9
77 s14 adjacent bricks, s21, team 3
78 s16 circle equation, s26,
79 s15 base, s17
80 s22 target 7
81 s28 s30
strategic guessing and checking
2009 2016 done
2016 state sprint 7 8 9 video 64
65= sprint 11 24 target 4 space diagonal of rectangular prism; Seeing Symmetry in Systems of Equations
66=sprint 6 18 20 geometry rectangles
67 sprint23 team 2 try out the numbers combinations
68 target 7 team 5
69 team 9 counting sprint 3
70 sprint17 target 1 sprint 28
71 sprint 26 team 7
2016 vid72 sprint 30 team 8; sprint 30 is 3D to 2D conversion problem!
be strategically lazy
get in there and do something
can't make website; videos are not good for learning math; get organized
acting out math;
divided by year - he skipped the 2 hardest problems of 2019.
https://artofproblemsolving.com/videos/mathcounts
30 https://youtu.be/UfxYpF7CYUs?list=PLF579ECF317F5DC48&t=837
cubing https://youtu.be/dG5jyGM2AV4?list=PLF579ECF317F5DC48&t=465
33 perfect square https://youtu.be/likQ5as2K7w?list=PLF579ECF317F5DC48
24 octhedron
34 silo
35 frustum https://youtu.be/FvNl3njneYE?list=PLF579ECF317F5DC48&t=660
43
44
https://youtu.be/9dFljwBK-aA?list=PLF579ECF317F5DC48
50 stacking cubes https://youtu.be/aNOLFe4g6AM?list=PLF579ECF317F5DC48
ants paths https://youtu.be/FSnpoU3jYZI?list=PLF579ECF317F5DC48
53 https://youtu.be/37ig50fQ_dI?list=PLF579ECF317F5DC48 polynomials 1/a+1/b+1/c+1/d
63 https://youtu.be/k7RuwNA2pIA?list=PLF579ECF317F5DC48
Mini #63 – Composed and Decomposed Area and Volume
66 https://youtu.be/T_dsqvKEw1c?list=PLF579ECF317F5DC48&t=306 2016 problem
67 chess board knight moves - logical shown
72 2016 last problem 12 sided die https://youtu.be/ezTIviytTi4?list=PLF579ECF317F5DC48
77 shown counting adjacent brick paths https://youtu.be/ZCPbpKUbQvQ?list=PLF579ECF317F5DC48
74 square with 4 hole in it, what's the 6th element to the right of 5? https://youtu.be/ckjwrN6sadA?list=PLF579ECF317F5DC48
76
81 https://youtu.be/LY9e571DrrI?list=PLF579ECF317F5DC48&t=533
79 bases
69 https://youtu.be/ieKWJgGwM78?list=PLF579ECF317F5DC48 in comments:
To find the number of rectangles in a grid, if n = the # of horizontal lines and m = the # of vertical lines, the number of rectangles is nC2 * mC2 (where C means combination) because to make a rectangle, you pick two horizontal lines and two vertical lines. In the first problem, there were 4 horizontal lines and 3 vertical lines. 4C2 * 3C2 = 6 * 3 = 18 rectangles.
geometry problems are easy`
95-89 89 now
95 https://youtu.be/YKFjtMqIuDc?list=PLF579ECF317F5DC48 quite good; later part has an elegant solution
83 https://youtu.be/btc-c34xYSw?list=PLF579ECF317F5DC48
magic square grids
mathcounts minis -
https://www.youtube.com/playlist?list=PLF579ECF317F5DC48
square difference formula - evil twin formula
shown to sandra beloew-
14 https://youtu.be/dHBPfoSQGI8 quadratic equation and modular arithmetic = quite good;
showed to sandra
84 https://youtu.be/5U4ESpBpCZk?list=PLF579ECF317F5DC48
trapezoids - rotate line to get area ratios; and rectangular segment length
get organized
2009 state sprint
14, video 1
prob of 3 dice rolling to sum 9? subcasing on largest number 6 5 4 3
know cubes 6^3=216
15 video 2 ABC race, can tie, how many ways to finish?
subcase criteria - # of ties or can also be #people in first place
0 tie - 6
3 tie - 1
2 tie first - 3
2 tie last - 3
Counting Methods/Number of Arrangements
target 2 and sprint 22 video 3
arithmetic sequence - gap 3 and 7 -> meet at 21
team 5 video 4
x+1/y=1, y+1/z=1, xyz=?
try out numbers; plug in any number, x=2 eg, y=-1, z=1/2; that gives xyz=-1
doing sth stupid
yz times eq 1; z time eq 2
or xyz=(1-1/y)yz=yz-z=z(y-1)=z(-1/z)=-1!
target 8 video 5 part 2 pigeon hold principle= monkey barrel principle
1-16, max number can draw before getting 2 multiple to a perfect square?
perfect squares
https://youtu.be/oyYYe-LOccI?list=PLF579ECF317F5DC48
2 poster problem video 6, constructive counting
2009 team 6 video 7
https://youtu.be/hWJn-c-tQcU?list=PLF579ECF317F5DC48&t=105
7 counting paths - go backwards
2009 team 7 video 8 Geometry/Auxiliary Lines & Special Right Triangles
seeing things not there, auxillary lines
2009 national team 6 video 9
telescoping -
2/1*3 + 2/2*4+2/3*5+2/4*6+...+2/2008*2010+2/2009*2011 = ?