Plz i need this asap, if you do not know all of them, plz do not answer

1. sqrt 52 = 7.211 rounds to 7

2. irrational number

3. sqrt 441 = 21rational

4. 12^2 + 3^2 = h^2
    144 + 9 = h^2
     153 = h^2
      sqrt 153 = h
      12.4 = h <===

5. 6^2 + b^2 = 18^2
    36 + b^2 = 324
    b^2 = 324 - 36
    b^2 = 288
    b = sqrt 288
    b = 16.97 rounds to 17 <==

6. 39^2 + 52^2 = c^2
    1521 + 2704 = c^2
    4225 = c^2
    sqrt 4225 = c
    65 = c
    (39 + 52) - 65 = 91 - 65 = 26 miles shorter <==

7. 4^2 + b^2 = 16^2
     16 + b^2 = 256
     b^2 = 256 - 16
     b^2 = 240
     b = sqrt 240
     b = 15.49 rounds to 15.5 <==

8. ?