Prime numbers and standard form key terminology crossword

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Across
  1. 2. a number that's only factors are 1 and itself
  2. 5. numbers we can multiply together to get another number
  3. 8. ___________tree a type of tree we use to work out the factors of a number. It can also be used to work out the HCF and the LCM of two or more numbers.
  4. 9. the first odd prime number
  5. 11. when working out if a number is prime, only numbers less than or equal to the __________ of the number being investigated need to be considered.
  6. 12. the only even prime number
  7. 13. to convert something into standard for we multiply by powers of _____
Down
  1. 1. what form is 3 x 10^4 written in
  2. 3. the result of multiplying a number by another number
  3. 4. 3.456 rounded to 3.46 is rounded to 2 _______ figures
  4. 6. One way of working out if a number is prime is by using the ______ method
  5. 7. Acronym for the smallest positive number that is a multiple of two or more numbers
  6. 10. acronym for the highest number that divides exactly into two or more numbers