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March 2020
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Daily Challenges

Math and Logic

Fill the Cross

Calcdoku puzzles don't allow repeat digits in any row or column, but repeats can happen in differently shaped regions. Can you repeat any digits in the center cross of this puzzle?

1,027 people working on this

Science and Engineering

Mysterious New Ornaments

Someone removed ornaments from your mobile and rebalanced it with new ornaments. What are their weights?

Series 5 of 5 5,171 people working on this

Saturday, March 28, 2020

Math and Logic

Not a Whole Circle

When we know the area of one of a pair of similar figures, finding the other area can be easier when we relate lengths instead of using area formulas. Find the area of the lune.

7,637 people working on this

Friday, March 27, 2020

Math and Logic

Pick the Right Number to Win

In some games, it's possible to play perfectly. What choice guarantees a win in this game?

9,186 people working on this

Thursday, March 26, 2020

Science and Engineering

Reflection Angle Wrangling

Adding a mirrored barricade to a reflection box introduces a new angle to this ray-tracing challenge.

Series 3 of 3 7,821 people working on this

Wednesday, March 25, 2020

Math and Logic

Take the Scenic Route

Finding the longest possible path between vertices in a network can come down to counting the lines from each vertex. There's an additional wrinkle in this problem, since some paths are straight while others are curved.

8,490 people working on this

Tuesday, March 24, 2020

Math and Logic

Even or Odd

With operator search puzzles, you can change the +, -, ×, and ÷ symbols of an equation. Think about how even and odd numbers combine by these operations when solving this puzzle.

9,232 people working on this

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