This is a puzzle that I found on the wall of the Sagrada Familia in Barcelona, Spain. It is a "cryptograma," a 4 x 4 matrix of seemingly random numbers that add up to 33 in over 300 different ways by choosing 4 numbers, which often create distinctive and unusual patterns.
Great for developing strategies for mental math, as well as divergent problem solving and just plain fun! Perfect for 2nd graders and up, and "advanced" 1st graders. The emphasis here is on MENTAL MATH. DO NOT USE THIS AS "PRACTICE" ON THE ADDITIONAL ALGORITHM, BECAUSE IT WILL DEFEAT THE PURPOSE OF THIS ACTIVITY.