Math Terminology/History
Math Riddle
Logic
Current PiSaders
PiSaders History
100

Who is credited with the sequence: 1,1,2,3,5,8,13,...

Fibonacci

100

There are seven apples on a tree, and you take away three. How many apples do you have?

3

100

Chloe and Eugenie ran a 100m sprint, and Chloe won, 10m ahead of Eugenie. In another race, if Chloe is 10m behind Eugenie, who will win? (They have the same pace as before)

Chloe

100

Who’s our new advisor addition for the 25-26 SY?

Ms. Lloyd

100

Who were the two CO25 Pisader executives last year?

Esther Nam, Chloe Shin

200

The 9th digit of pi

5 (3.14159265)

200

What is the smallest whole number that is equal to seven times the sum of its digits?

21

200

The doctor gives you 4 tablets: 2 blue tablets and 2 red tablets. You’re color blind, but you need to take exactly 1 red and 1 blue tablet. How do you make sure you survive?

Cut half of each tablet and get one half from each tablet. 

200

What’s the username of the PiSaders instagram account?

sfhspisaders

200

Who were the advisors of PiSaders in the 23-24 SY?

Mr. Kneeshaw & Mr. Wilson

300

Is the number of permutations of a deck of cards greater than or smaller than the number of atoms in the solar system?

Greater than; 8.0658*10^67 vs, 10^57~10^58

300

How can Kate measure exactly 15 minutes with a 7-minute and an 11-minute hourglass?

Start both, flip 7 minute after 7-minute runs out. Flip 7 when 11-minute runs out. When 7-minute hourglass runs out, 15 minutes passed.

300

If Eason has 30 red socks, 20 blue socks, and 6 yellow socks, how many does he have to pick to get at least 1 matching pair without looking?

4

300

How many accounts does the PiSaders Instagram follow?

2

300

How many CO25 general members were in PiSaders last year?

10

400

What is arguably the most important unsolved mathematical problem today?

The Riemann Hypothesis

400

Three people all have a tendency to lie 1/3 of the time. They all see a coin flip. They all say it's Heads. What's the probability it is actually Heads?

8/9
400

Olivia has 9 same-sized balls with the same mass, except for one that is heavier.

How would she find the heavier ball if she could use a pair of balance scales only twice?

Divide the 9 balls into 3 groups of 3. Choose 2 balls from the different groups.

400

When did we send out our PiSaders email about the fall application for this school year?

September 8

400

In what month did PiSaders host the Waterloo Math Competition at SFS in the 24-25 SY?

April

500

What is the tremendously large finite number that is a proven upper bound to the solution of a certain problem in Ramsey theory?

Graham's number

500

You have two ropes and a lighter. Each rope takes 1 hour to burn from one end to the other. Without folding or cutting the ropes, how do you measure 45 minutes?

Burn each end of rope #1 and burn one end of rope #2. When rope #1 is completely burned (30 mins), burn the other end of rope #2 (30/2 mins = 15 mins).

500

100 passengers board a fully booked plane. The first picks a random seat. Each next passenger takes their own seat if free, otherwise a random one. What is the probability the last passenger sits in their assigned seat?

50%

500

When is the competition date for this year’s UKMT Senior Math Competition?

October 9, 2025

500

The external school with the highest number of participants in the 2024 SFS Middle Years Math Competition

YISS

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