Factors of 40

How to find the factors of 40

Test every whole number from 1 up to the square root of 40 (√40 ≈ 6.325). Each number that divides evenly gives you two factors at once: the divisor and the quotient.

• 40 ÷ 1 = 40 — so 1 and 40 are factors
• 40 ÷ 2 = 20 — so 2 and 20 are factors
• 40 ÷ 3 = 13.333 — not a whole number
• 40 ÷ 4 = 10 — so 4 and 10 are factors
• 40 ÷ 5 = 8 — so 5 and 8 are factors
• 40 ÷ 6 = 6.667 — not a whole number

Collecting both numbers from every successful division gives the complete list: 1, 2, 4, 5, 8, 10, 20 and 40.

Prime factorization of 40

Divide by the smallest prime that fits, and keep going until the quotient is 1:

The primes you divided by give 40 = 2³ × 5. From the exponents you can also count the factors without listing them: (3 + 1) × (1 + 1) = 8.

Properties of 40

• 40 is a composite number.
• The sum of all its factors is 90; the sum of its proper factors (excluding 40) is 50, which makes it a abundant number (its proper factors add up to more than itself).
• 40 is not a perfect square, so its factors pair up evenly.
• Multiples of 40 include 80, 120, 160, 200 and so on.

Factors vs. multiples

Factors of 40 are the numbers that divide into it; multiples of 40 are the numbers it divides into. Every number has a limited set of factors but infinitely many multiples. To work with any other number, use the factors calculator, or find shared factors with the GCF calculator.