To find how approximately how many moons could fit inside the earth, you would need yo find the volumes the earth and the moon.
V = 4/3 π r^3
Earth:
d = 2r
d = 7926 miles
7926 = 2r
3963 miles = r
V = 4/3 π (3963)^3
V = 4/3 π (62240377347)
V = 82987169796π cubic miles
Moon:
d = 2r
d = 2159 miles
2159 = 2r
1079.5 miles = r
V = 4/3 π (1079.5)^3
V = 4/3 π (1257963209.88)
V = 1677284279.83π cubic miles
Now you divide the volume of earth by the volume of moon to find how many moons can fit in earth
82987169796π ÷ 1677284279.83π =
approx 49
Rounding to the nearest whole number, 49 moons can fit in the earth.
Rounding to the tenth place, 50 moons can fit in the earth.