Leonhard Euler Crossword

1234567
Across
  1. 2. He was born to one of these
  2. 4. (V-E+F=2.)
  3. 6. His field of math
  4. 7. Got a masters degree
Down
  1. 1. he changed this item
  2. 3. He studied under this person
  3. 5. He made this theory