It is generally a good idea to gain an understanding of the "size" of units. Consider the objects listed and calculate the magnitude of their momentum in SI units. A ladybug weighing 31.80 mg flies by your head at 2.53 mi/h.

The standard unit of momentum Is kgm/s

And momentum is the product of mass and velocity

Then,

Momentum = mass * velocity

P = mv

Where

m is mass in kg

v is velocity in m/s

Now,

Given that,

M = 31.8mg

1mg = 10^-3g

So, m = 31.8 * 10^-3g

Also, 1000g = 1kg → 1g = 10^-3 kg

So,

m = 31.8 * 10^-3 * 10^-3kg

m = 31.8 * 10^-6 kg

v = 2.53mi/hr

1mile = 1609.34 m

1 hour = 3600seconds

Then,

v = 2.53 * 1609.34m / 3600s

v = 1.13 m/s

So, momentum is given as

P = mv

P = 31.8 * 10^-6 * 1.13

P = 3.597 * 10^-5 kgm/s