Math crossword puzzle

12345678910111213
Across
  1. 3. equal
  2. 4. up and down
  3. 6. the opposite of multiplication
  4. 7. a number to another number
  5. 8. to help find the constant
  6. 11. the opposite of addition
  7. 13. one is acute
Down
  1. 1. side to side
  2. 2. to add faster
  3. 5. the opposite of subtraction
  4. 9. holds lots of information
  5. 10. something that keeps going
  6. 12. to learn numbers