Using pythagorean theorem :
[tex]a {}^{2} = b {}^{2} + c {}^{2} \\ \\ c {}^{2} = 4 {}^{2} + 6 {}^{2} \\ \\ c {}^{2} = 16 + 36 \\ \\ c {}^{2} = 52 \\ \\ c = \sqrt{52} \\ \\ 7 {}^{2} = 49 \\ \\ 8 {}^{2} = 64 \\ \\ 7 < c < 8[/tex]
Answer: about seven
