Mathematics

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Across
  1. 2. A solid that has 5 faces one of which is a square
  2. 3. An angle smaller than 90°
  3. 4. Problem, Plan, Data, Analysis, and Conclusion
Down
  1. 1. the fundamental of mathematics that includes the operations of numbers
  2. 2. 3.1415926535 8979323846 2643383279 5028841971 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679
  3. 5. the action or process of adding something to something else.