The graph between |ψ| ^ 2 and r (radical distance) is shown below....

This graph shows one radial node
Formula of radial node $= n - l - 1$ ; angular node $= l$ ; total node $= n - 1$
$n =$ Principal quantum number
$l =$ Azimuthal quantum number

Radial nodes:

for $1s$ $= n - l - 1 = 1 - 0 - 1 = 0$
for $2s = 2 - 0 - 1 = 1$
for $2p = 2 - 1 - 1 = 0$
for $3s = 3 - 0 - 1 = 2$