Maths

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Across
  1. 4. What type of numbers are 2, 5, 7 and 19 examples of. (5)
  2. 5. The numbers of sides a triangle has. (5)
  3. 6. The percentage which is equal to 3/5. (5)
  4. 7. The operation of 'taking away'. (11)
Down
  1. 1. The substitution of numbers for letters for example 2+a=5
  2. 2. The number of minutes in a quarter of an hour (7)
  3. 3. The number of weeks in a year. (5,3)
  4. 6. The shape that has four equal sides and four equal angles.(6)