Problem 32: Taking Turns to Toss a Die

from: Cut the Knot

Problem 31: Easy Hand-Sketch Puzzle for Primary

Problem 30: Basic Knot Puzzle

Problem 29: Numbers in circles

The figure shows seven circles joined by three straight lines. The numbers 9, 12, 18, 24, 36, 48 and 96 are to be placed into the circles, one in each so that the product of the three numbers on each of the three lines is the same. Which of the numbers could go in the center?

Source: UKMT

Math Pics 3: Perceptions of Probability and Numbers

Source

Rich Tasks 4: Number Challenge

Problem 28: World Cup Standing

In the World Cup’s group stage, each group of four teams plays a round robin, with every team playing the other teams once each. A win is worth 3 points, a draw 1 point, and a loss 0 points. The points are tallied, and the top two teams in each group advance to the knockout stage. For a given group — let’s pick Group A, which includes Russia, Saudi Arabia, Egypt, and Uruguay — how many different final standings, including point totals, are possible for the group stage?

Source: fivethirtyeight

Rich Tasks 3: Number Crossword Challenge

Prepare a number crossword using prime numbers, square and cubic numbers. Your target is to complete it with the least amount of dark squares.

Downloadable Link

Math Pics 2: Illusion

Problem 27: Three Candles

When one of the three equal-sized candles completely melted, the second has a height of 3 cms and the third one has a height of 5 cms.

At the instant when the second candle totally finishes, the third candle's length is measured 2.5 cms.

What was the initial length of the candles?

Problem 26: Logic Puzzle

Which of the following is most suitable for the missing place?

Problem 25: Missing Number

Find the missing number:

Problem 24: Count the Circles

 How many circles will there be in step IV?

Problem 23: Missing Figure

 

Which of the following is the most suitable for the missing position?

Problem 22: Squares and Cubes Password

Source

Beautiful Gifs 5: π

Problem 21: Shaded Area

Teaching Ideas 1: Variation Theory

Resource: Naveen Rizvi

Problem 20: Order of Solids

Sandra places the given cards on a table as shown. Which of the following is the card placed the fifth?

Problem 19: Next Number in the Sequence

1, 1, 2, 3, 3, 5, 4, 6, 5, 9, 6, 9, 7, 13, 8, 12, 9, 17, 10, 15, 11, 21, 12, 18, 13, 25, 14, ?

Beautiful Gifs 4: Dynamic Müller-Lyer Illusions by Gianni A. Sarcone

Sarcone, Gianni A. "Dynamic Müller-Lyer Illusion." From Sarcone’s Studio -- A Sarcone & Waeber 

https://www.giannisarcone.com/Muller_lyer_illusion.html
Copyright © G. Sarcone

Problem 18: Skipping Sevens

Mauricio counts from 1 to 200. Believing that ‘7’ is not a lucky number for him, he skips all the multiples of seven and all the numbers that contain seven. In this situation, how many numbers does he skip?

Problem 17: Handshakes

UEFA Pre-Match Handshake   ©Getty Images

Before a football game starts each team player shakes hands of all other team players and the referees. There are 11 players in a football team and there are 3 referees for the game, in the pre-match ceremony. How many handshakes will there be in total?

1. 124
2. 155
3. 188
4. 242
5. 255

Problem 16: Polygon Puzzle

Problem 15: Odd Figure

Choose the odd one out!

Problem 14: Triangles

Problem 13: Circles inside the square

The pink circle has radius R, and orange circle has radius r.

Find the length of R in terms of r.

This problem is moderated from here.