These are some of the most important numbers that every programmer should know. The second(Power of 2s) and 3rd(time units in terms of seconds) are quite obvious but I like to keep them in place so that I can remember them quickly. However, the most important one is Jeff Dean’s numbers. Here we go:
Jeff Dean’s Numbers
Credits - https://gist.github.com/jboner/2841832
Base 2 Exponents
$$ \begin{align*} 2^0 &= 1\\ 2^1 &= 2\\ 2^2 &= 4\\ 2^3 &= 8\\ 2^4 &= 16\\ 2^5 &= 32\\ 2^6 &= 64\\ 2^7 &= 128\\ 2^8 &= 256\\ 2^9 &= 512\\ 2^{10} &= 1024\\ 2^{11} &= 2048\\ 2^{12} &= 4096\\ 2^{13} &= 8192\\ 2^{20} &= 1,048,576\\ 2^{30} &= 1,073,741,824 \end{align*} $$
Time Units in seconds
$$
\begin{aligned}
1 & ns& &= 10^{-9}\\
1 & us& &= 10^{-6}\\
1 & ms& &= 10^{-3}\\
1 & sec& &= 1\\
1 & min& &= 60\\
1 & hour& &= 3600\\
1 & day& &= 86400\\
1 & week& &= 604,800 ~ 6 * 10^5\\
1 & month& &= 18,144,000\\
1 & year& &= 217,728,000\\
\end{aligned}
$$