A body moves $1250 \mathrm{m}$ in $11\mathrm{s}$. Find its average speed in correct number of significant figures.

Solve $\frac{2.91\times 0.3842}{0.080}$ with due consideration of significant figures.

In a simple pendulum experiment, the measured length of the pendulum is $90.6\times {10}^{-2} \mathrm{m}$ and the period of oscillation is $1.91 \mathrm{s}$. Find the value of acceleration due to gravity up to correct significant figures.

The measured mass and diameter of a uniform brass ball are $29.150\times {10}^{-3} \mathrm{Kg}$ and $1.92\times {10}^{-2} \mathrm{m}$ respectively. Express the density of brass in appropriate significant figures.

Express the number of seconds in a day in a year in orders of magnitude.

The number of protons and neutrons in the universe is of the order of ${10}^{82}$ and that in the sun is of the order of ${10}^{57}$. If we assume that all stars are of the same mass as the mass of sun, then what would be the order of the number of stars in the universe?

If an atom$($size$={10}^{-10} \mathrm{m})$ were enlarged to the size of earth$(\cong {10}^7\mathrm{m})$, how large would its nucleus$(\cong {10}^{-15}\mathrm{m})$be? 

If the universe$(\cong {10}^{26}\mathrm{m})$ were to shrink to the size of earth$(\cong {10}^7\mathrm{m})$, how large would the earth be?

The heart beats once in $0.8 \mathrm{s}$. Find the number of times the heart beats in the life of $60$ years of a man.