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# SI Prefixes

• You probably learned these in science class but just in case.
• We will care about
• pico - tera at least.
• NameSymbol Base 10
tera T $10^{12}$
giga G $10^9$
mega M $10^6$
kilo k $10^3$
mili m $10^{-3}$
micro $\mu$ $10^{-6}$
nano n $10^{-9}$
pico p $10^{-12}$
• exa, zetta, and possibly yotta are something you should be aware of.
• Name something that is measured in each unit.
• In general, we like to keep numbers between 1 and 1000.
• I have a file that is 102,304,288 bytes.
• Represent this in scientific notation: $1.02 \times 10^{11} \text{bytes}$
• Since I want the value to be between 1 and 1,000, I will covert to $10^9$ bytes per 1 Gb.
• $1.02 \times 10^{11} \text{bytes} \times \frac{1Gb}{10^9 \text{bytes}}$
• $1.02 \times 10^{\cancel{11}2} \cancel{\text{bytes}} \times \frac{1Gb}{10^{\cancel{\text{9}}1}\cancel{\text{bytes}}}$ The 9 in the denominator should be crossed out
• $1.02 \times 10^2 Gb = 102 Gb$
• I know this sounds silly, you can just do this one in your head, but practice it for me please.
• We could have converted this to .1Tb, but this is not normal.
• A note on binary prefixes.
• Like, Santa, they do exist.
• See This reference
• Generally they are powers of 2 or 1024.
• Value2Name Symbol
$1024$ $2^{10}$ kibi Ki
$1024^{2}$ $2^{20}$ mebi Mi
$1024^{6}$ $2^{30}$ gibi Gi
$1024^{9}$ $2^{40}$ tebi Ti
$1024^{12}$ $2^{50}$ pebi Pi
$1024^{15}$ $2^{60}$ exbi Ei