# Number and Quantity

Pro Problems > Math > Number and Quantity# Featured Pro Problems

Without a calculator find a nine digit number that meets the criteria of the problem

A math problem involving Shrek wanting Fiona's telephone number

Multiply a three by one matrix and a one by three matrix

Strings of red lights and green lights on my Christmas tree - a Christmas word problem

Solve for x in this matrix multiplication equation

Find the value of w in the matrix multiplication problem

A diophantine equation - quadratic in two variables

Use divisibility rules to determine the number with missing digits

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The Value of a Word, Trick-or-Treat Math, Two Numbers# Understanding Coronavirus Spread

A Question and Answer session with Professor Puzzler about the math behind infection spread.

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