{
 "source": "https://peabody.kids/flashcards/math-number-types",
 "id": "math-number-types",
 "title": "Types of Numbers",
 "category": "math",
 "subject": "Math",
 "levels": [
  "3-5",
  "6-8",
  "9-12"
 ],
 "description": "Natural, whole, integer, rational, irrational, real and special number families.",
 "tags": [
  "number systems",
  "number sense"
 ],
 "frontLabel": "Term",
 "backLabel": "Meaning",
 "cards": [
  [
   "Natural (counting) numbers",
   "1, 2, 3, 4, ..."
  ],
  [
   "Whole numbers",
   "0, 1, 2, 3, ..."
  ],
  [
   "Integers",
   "..., −3, −2, −1, 0, 1, 2, 3, ..."
  ],
  [
   "Rational numbers",
   "Numbers that can be written as a fraction of two integers"
  ],
  [
   "Irrational numbers",
   "Numbers that cannot be written as a fraction"
  ],
  [
   "Real numbers",
   "All rational and irrational numbers"
  ],
  [
   "Imaginary numbers",
   "Multiples of i, where i² = −1"
  ],
  [
   "Complex numbers",
   "Numbers of the form a + bi"
  ],
  [
   "Even numbers",
   "Whole numbers divisible by 2"
  ],
  [
   "Odd numbers",
   "Whole numbers not divisible by 2"
  ],
  [
   "Prime numbers",
   "Numbers above 1 with exactly two factors"
  ],
  [
   "Composite numbers",
   "Numbers above 1 that are not prime"
  ],
  [
   "Square numbers",
   "1, 4, 9, 16, 25, ..."
  ],
  [
   "Cube numbers",
   "1, 8, 27, 64, 125, ..."
  ],
  [
   "Triangular numbers",
   "1, 3, 6, 10, 15, 21, ..."
  ],
  [
   "Fibonacci numbers",
   "1, 1, 2, 3, 5, 8, 13, 21, ..."
  ],
  [
   "Perfect numbers",
   "Numbers equal to the sum of their proper factors: 6, 28, 496"
  ],
  [
   "Is 6 perfect?",
   "Yes: 1 + 2 + 3 = 6"
  ],
  [
   "Is 28 perfect?",
   "Yes: 1 + 2 + 4 + 7 + 14 = 28"
  ],
  [
   "Palindromic number",
   "A number that reads the same backward and forward",
   "121"
  ],
  [
   "Twin primes",
   "Primes that differ by 2",
   "11 and 13"
  ],
  [
   "Mersenne prime",
   "A prime of the form 2ⁿ − 1",
   "7, 31, 127"
  ],
  [
   "Pi is rational or irrational?",
   "Irrational"
  ],
  [
   "√2 is rational or irrational?",
   "Irrational"
  ],
  [
   "√9 is rational or irrational?",
   "Rational (it equals 3)"
  ],
  [
   "0.5 is rational or irrational?",
   "Rational"
  ],
  [
   "0.333... is rational or irrational?",
   "Rational (1/3)"
  ],
  [
   "Is e rational or irrational?",
   "Irrational"
  ],
  [
   "Is zero positive or negative?",
   "Neither"
  ],
  [
   "Is zero even?",
   "Yes"
  ],
  [
   "Is 1 prime?",
   "No"
  ],
  [
   "Is 0 an integer?",
   "Yes"
  ],
  [
   "Is −4 a whole number?",
   "No"
  ],
  [
   "Is −4 an integer?",
   "Yes"
  ],
  [
   "Is 3/4 an integer?",
   "No, it is rational"
  ],
  [
   "Is every integer a rational number?",
   "Yes (n = n/1)"
  ],
  [
   "Is every rational number an integer?",
   "No"
  ],
  [
   "Is every real number rational?",
   "No"
  ],
  [
   "Ordinal numbers",
   "First, second, third: tell position"
  ],
  [
   "Cardinal numbers",
   "One, two, three: tell how many"
  ],
  [
   "Nominal numbers",
   "Numbers used as names or labels, like a jersey number"
  ],
  [
   "Opposite of 7",
   "−7"
  ],
  [
   "Reciprocal of 7",
   "1/7"
  ],
  [
   "Absolute value of −7",
   "7"
  ],
  [
   "Negative of a negative",
   "A positive: −(−7) = 7"
  ],
  [
   "Googol",
   "10^100"
  ],
  [
   "Googolplex",
   "10 to the power of a googol"
  ],
  [
   "Infinity",
   "Not a number; the idea of going on without end"
  ],
  [
   "Golden ratio",
   "About 1.618, an irrational number: (1 + √5)/2"
  ]
 ]
}