LCM for 12, 20 and 40

"Least Common Multiple of 3 Numbers" Calculator
Least Common Multiple of
,
and

What's the Least Common Multiple (LCM) of 12, 20 and 40?

Answer

LCM of 12, 20 and 40 is
120

(One hundred twenty)

120 is the smallest positive integer that 12, 20 and 40 all divide without a remainder — every other common multiple of the three is a multiple of it.

Finding the LCM of 12, 20 and 40 by Prime Factorization

Split all three numbers into prime factors, then take every prime that shows up in at least one of them, each raised to the highest power it reaches there. Multiplying those highest powers gives the least common multiple:

All Prime Factors of 12: 2 × 2 × 3 (exponent form: 22 × 3)

All Prime Factors of 20: 2 × 2 × 5 (exponent form: 22 × 5)

All Prime Factors of 40: 2 × 2 × 2 × 5 (exponent form: 23 × 5)

Prime factor122040Highest power
222222323
33——3
5—555

LCM = 23 × 3 × 5 = 120

Checking the LCM of 12, 20 and 40 Two Numbers at a Time

The least common multiple is associative, so three numbers can be handled as two pairs: first the LCM of the first two, then the LCM of that value and the third. Each pair goes through the two-number formula, which uses the greatest common divisor:

LCM(a, b) = (a × b) ÷ GCD(a, b)

LCM(12, 20) = (12 × 20) ÷ 4 = 240 ÷ 4 = 60

LCM(60, 40) = (60 × 40) ÷ 20 = 2,400 ÷ 20 = 120

LCM(12, 20, 40) = 120

The pairs may be taken in any order — 20 and 40 first, then 12 — and the answer is the same 120. That is exactly why the two routes on this page agree.

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About "Least Common Multiple of 3 Numbers" Calculator

This calculator finds the Least Common Multiple (LCM) of three numbers at once, without doing it in two passes. For example, it can help you find out what's the Least Common Multiple (LCM) of 12, 20 and 40? (The answer is: 120). Enter the first number (e.g. '12'), the second (e.g. '20') and the third (e.g. '40'), then hit the 'Calculate' button.
The Least Common Multiple of three numbers is the smallest positive integer that all three of them divide without a remainder
"Least Common Multiple of 3 Numbers" Calculator
Least Common Multiple of
,
and

LCM Table

Number 1Number 2Number 3LCM
122025300
122026780
122027540
122028420
1220291,740
12203060
1220311,860
122032480
122033660
1220341,020
122035420
122036180
1220372,220
1220381,140
122039780
122040120
1220412,460
122042420
1220432,580
122044660
122045180
1220461,380
1220472,820
122048240
1220492,940
122050300
1220511,020
122052780
1220533,180
122054540

FAQ

What's the Least Common Multiple (LCM) of 12, 20 and 40?

LCM of 12, 20 and 40 is 120

How to find the LCM of 12, 20 and 40 by prime factorization?

Take every prime that appears in 12, 20 and 40 to the highest power it reaches in any one of them and multiply: 2³ × 3 × 5 = 120.

Can you get the LCM of 12, 20 and 40 two numbers at a time?

Yes, and it is the check this page prints. The LCM of 12 and 20 is 60, and the LCM of 60 and 40 is 120 — the same answer, because the least common multiple is associative and does not depend on the order of the three numbers.

Is 120 divisible by 12, 20 and 40?

Yes, and by definition it is the smallest positive integer that is: 120 ÷ 12, 120 ÷ 20 and 120 ÷ 40 all come out whole. Any other common multiple of 12, 20 and 40 is a multiple of 120.

See Also