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What is an integer?

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Quick answer

An integer is a whole number — it can be positive, negative, or zero, but never a fraction or decimal. …, −3, −2, −1, 0, 1, 2, 3, … are all integers. They're the numbers you count with, plus their negatives and zero.

Key things to understand

  1. Integers are whole numbers: positive (1, 2, 3), negative (−1, −2, −3), and zero.
  2. They have NO fractional or decimal part — 5 is an integer, but 5.5 and ½ are not.
  3. Positive integers are the counting numbers; adding negatives and zero gives all integers.
  4. Integers can be added, subtracted, and multiplied to give other integers.
  5. They sit on the number line at evenly spaced whole-number points.

People also ask

Is zero an integer?
Yes. Zero is an integer — it's neither positive nor negative, but it's a whole number, so it counts.
Is a decimal or fraction an integer?
No. Integers have no fractional part. 7 is an integer; 7.5 and ¾ are not, because they fall between whole numbers.
What's the difference between an integer and a natural number?
Natural numbers are the positive counting numbers (1, 2, 3…), sometimes including 0. Integers also include the negatives (…, −2, −1).