Difference between revisions of "Math for CS Review"

Note - Khan Academy Math is a good resource to look up and refresh general math knowledge. Khan Academy AP CS Principles and Khan Academy Computing also have some content related to math embedded within them.

Memorize

These are things you need to memorize.

• Order of operations: first parenthesis, then exponents, then multiplication/division/modulus, then addition and subtraction. And left to right.
• Powers/exponents
• 210 = 1024, roughly 1 thousand
• 2a+b = 2a * 2b
• ya+b = ya * yb
• 2-a = 1 / (2a)
• 220 = 1024 × 1024, roughly 1 million
• 230 = 1024 × 1024 × 1024, roughly 1 billion
• Logarithms
• logbx = y, means by = x, for any b > 1
• log101000 = 3
• log21024 = 10
• logbx = logcx / logcb, for any b > 1, c > 1
• logb(xy) = y logb x, for any b > 1
• logb(x y) = logb x + logb y, for any b > 1
• Formulae
• Arithmetic Sum: (1 + 2 + ... + n) = n * (n+1) / 2
• Geometric Sum: 1 + r + r2 + r3 + ... + rn = (rn+1-1) / (r-1)
• Boolean logic
• Possible values - true, false - can mean on, off - often represented by 1, 0