number, strength, fate, law, figures
数 centers on counting and the results of counting: numbers, figures, and quantities. The extended senses of fate and law come from the idea of a fixed, counted order, while strength can be seen as a counted measure of power.
several; a few; a number of
number; amount
large number (of); many
plural; multiple
the number of people
numeral; digit; numeric character
number of times; frequency; count
mathematics
numerical value
small number; few; minority
many; numerous; various; large number of
(handling) fee; charge (e.g. for a cancellation); commission; brokerage
in great numbers
marks; points; score; grade; runs (baseball)
frequency (esp. of waveforms)
the number of flat things
quantity; volume; amount
index; index number; indicator
number of days
half the number; half (of an amount)
few in number
innumerable; countless; numberless
fixed number; quorum (for an assembly)
number (of long, cylindrical things, movies, trains, home runs, etc.)
数 is the modern simplified form of 數. The older form combines 婁 (a phonetic component with the idea of tying or binding) and 攵 (a hand with a stick, suggesting an action). Together they expressed counting or reckoning, possibly from the idea of tying knots to keep count.
The left side 娄 looks like a woman 女 with something on top, and the right side 攵 is a hand holding a stick. Imagine a woman keeping count by making marks with a stick: that's 数, the act of numbering.
For スウ, imagine counting numbers while sipping a hot soup: soup -> スウ, and the steam rises as you count.