What are the factor pairs of 128?

The pairs are (1, 128), (2, 64), (4, 32) and (8, 16). Each pair multiplies to 128.

What is the greatest common factor of 128 and 192?

The GCF of 128 and 192 is 64. The common factors are 1, 2, 4, 8, 16, 32 and 64, and 64 is the largest.

Factors of 128 - Factor Pairs & Prime Factorization

Q: What are the factors of 128?

The factors of 128 are 1, 2, 4, 8, 16, 32, 64 and 128. That is eight factors, and each one divides 128 exactly.

Q: What is the prime factorization of 128?

128 = 2 × 2 × 2 × 2 × 2 × 2 × 2 = 2⁷. Its only prime factor is 2.

What Are the Factors of 128?

The number 128 is 2 to the power 7, which is why it appears in computer memory sizes and in the 128 characters of ASCII. Every one of those tidy splits is a factor: a whole number that divides another number exactly, with no remainder.

The factors of 128 are 1, 2, 4, 8, 16, 32, 64 and 128. That is eight factors.

Factor Pairs of 128

Look for pairs that multiply to 128, working from the outside in.

Handwritten notebook page titled Factors of 128 showing 1 × 128, 2 × 64, 4 × 32, 8 × 16 all equal to 128, with the eight factors 1, 2, 4, 8, 16, 32, 64 and 128 circled in red and the note 8 factors — The 4 pairs of 128, with every factor circled.

Start with 1 × 128.
Try 2. Since 128 ÷ 2 = 64, write 2 × 64.
Try 4. Since 128 ÷ 4 = 32, write 4 × 32.
Try 8. Since 128 ÷ 8 = 16, write 8 × 16.
Keep trying whole numbers until you reach 16, which is already in your list. Every factor is now found, so you are done.

Prime Factorization of 128

Prime factors show what 128 is built from. Split it and keep going until every branch is a prime.

Handwritten factor tree of 128 splitting down to the circled primes 2, 2, 2, 2, 2, 2 and 2, with 128 = 2 × 2 × 2 × 2 × 2 × 2 × 2 = 2⁷ written below — Factor tree of 128. The circled primes are 2, 2, 2, 2, 2, 2 and 2.

So 128 = 2 × 2 × 2 × 2 × 2 × 2 × 2 = 2⁷. Its only prime factor is 2. Add 1 to each exponent and multiply: (7 + 1) = 8, which matches the list.

Divisibility check for 128

A number is a multiple of 128 when you can halve it 7 times in a row with no remainder. Take 384: halving gives 192, 96, 48, 24, 12, 6 and 3, which is seven halvings with no remainder, so 384 is a multiple of 128.

Is 128 a Prime or Composite Number?

Composite. It has eight factors. The sum of all factors is 1 + 2 + 4 + 8 + 16 + 32 + 64 + 128 = 255. The factors smaller than 128 add up to 127, which is less than 128, so 128 is called a deficient number.

Real-Life Uses of the Factors of 128

ASCII. The ASCII character set has 128 characters, since 128 = 2⁷.
Memory. Powers of 2 like 128 are everywhere in computer storage sizes.
Halving. You can halve 128 seven times in a row and stay with whole numbers.

Common Factors of 128 With Other Numbers

The factors of 192 are 1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 48, 64, 96 and 192, so 128 and 192 share 1, 2, 4, 8, 16, 32 and 64. The GCF is 64, which simplifies 128/192 to 2/3.

Quick Practice

Which of these are factors of 128: 5, 8 or 7? Only 8. Now try 180 and check it with the calculator.

Factors of 128