Labels
- 2D spatial reasoning
- 3D spatial reasoning
- alternate number bases
- area problems
- consecutive numbers and other sequences
- counting problems
- factors and multiples
- finding and extending patterns
- fractions
- geometry
- graph theory
- logic
- nets
- number bond practice for young children
- place value
- practice with addition/subtraction
- practice with decimal arithmetic
- practice with multiplication
- reflections/rotations

Sunday, February 28, 2021
Sunday, April 12, 2020
Drafter's Puzzle #2
A solid figure cut out of a cube looks like this in 2 dimensions when viewed from the front, back, and top. Notice that it has a horizontal edge visible from the front but not from the top. What could the solid look like?
Notice that it cannot look like this. Otherwise we would see an edge from the top too!
What does the solid look like? There are various possibilities. Click HERE for the solution.
Thursday, April 9, 2020
Spatial thinking challenge
The figures below are all cut out of identical cubes.
The diagram below shows the front view of the figures in two dimensions.
Question: What would the figures look like from the top in two dimensions? Strangely, four of them look the same from above. Which one is different?
For the solution, click HERE.
Tuesday, March 24, 2020
The Funny Calculator
Just like a “normal” calculator,
When you type 1 x 10, it says 10.
When you type 1 + 10, it says 11.
When you type 1 + 1, it says 10.
When you type 10 + 10, it says 100.
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Using this information alone:
How would you count from one to four?
What would the calculator say if you typed in 100 / 10 ?
Extending the pattern:
Can you extend the pattern to count up to twenty?
What would the calculator say if you typed in 0.1 + 0.1?
What would the calculator say if you typed in 0.1 x 10 ?
What would the calculator say if you typed in 111 + 111 ?
What would the calculator say if you typed in 111 x 10 ?
How would you count from one to four?
What would the calculator say if you typed in 100 / 10 ?
Extending the pattern:
Can you extend the pattern to count up to twenty?
What would the calculator say if you typed in 0.1 + 0.1?
What would the calculator say if you typed in 0.1 x 10 ?
What would the calculator say if you typed in 111 + 111 ?
What would the calculator say if you typed in 111 x 10 ?
For the solution, click HERE.
Saturday, March 21, 2020
Sunday, September 1, 2019
Digital Clock Problem
The clock below uses columns of dots to represent the time, in minutes and hours. What time does the clock read?
Use the clues below to decode the number system and read the time on the clock above.
Clues:
Here is the solution:
Each column represents a different power of 4. And the number of dots tells you how many 1s, 4s, and 16s you have. One way to see this is to start with the 8:04 clock and focus on the minutes. It takes only one dot to make the number :04, so the single dot must have that value. Then look at the 9:20 clock and again focus on the minutes. It takes 2 dots to make :20. One of those dots, we now know, is worth 4, so the other must be worth 16.
All together the dots on the mystery clock represent:
4 + 4 + 1 + 1 hours, and
16 + 1 + 1 + 1 minutes, so
10:19
Friday, August 30, 2019
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