LCM for 280, 360 and 840
What's the Least Common Multiple (LCM) of 280, 360 and 840?
Answer
(Two thousand five hundred twenty)
2,520 is the smallest positive integer that 280, 360 and 840 all divide without a remainder — every other common multiple of the three is a multiple of it.
Finding the LCM of 280, 360 and 840 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 280: 2 × 2 × 2 × 5 × 7 (exponent form: 23 × 5 × 7)
All Prime Factors of 360: 2 × 2 × 2 × 3 × 3 × 5 (exponent form: 23 × 32 × 5)
All Prime Factors of 840: 2 × 2 × 2 × 3 × 5 × 7 (exponent form: 23 × 3 × 5 × 7)
| Prime factor | 280 | 360 | 840 | Highest power |
|---|---|---|---|---|
| 2 | 23 | 23 | 23 | 23 |
| 3 | — | 32 | 3 | 32 |
| 5 | 5 | 5 | 5 | 5 |
| 7 | 7 | — | 7 | 7 |
LCM = 23 × 32 × 5 × 7 = 2,520
Checking the LCM of 280, 360 and 840 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(280, 360) = (280 × 360) ÷ 40 = 100,800 ÷ 40 = 2,520
LCM(2,520, 840) = (2,520 × 840) ÷ 840 = 2,116,800 ÷ 840 = 2,520
LCM(280, 360, 840) = 2,520
The pairs may be taken in any order — 360 and 840 first, then 280 — and the answer is the same 2,520. That is exactly why the two routes on this page agree.
Related Calculations
See Also
- Greatest Common Factor of 3 Numbers - Find the Greatest Common Factor (GCF) of three numbers
- Least Common Multiple - Find the Least Common Multiple (LCM) of two numbers
- Greatest Common Factor - Find the Greatest Common Factor (GCF) of two numbers

LCM Table
| Number 1 | Number 2 | Number 3 | LCM |
|---|---|---|---|
| 280 | 360 | 825 | 138,600 |
| 280 | 360 | 826 | 148,680 |
| 280 | 360 | 827 | 2,084,040 |
| 280 | 360 | 828 | 57,960 |
| 280 | 360 | 829 | 2,089,080 |
| 280 | 360 | 830 | 209,160 |
| 280 | 360 | 831 | 698,040 |
| 280 | 360 | 832 | 262,080 |
| 280 | 360 | 833 | 299,880 |
| 280 | 360 | 834 | 350,280 |
| 280 | 360 | 835 | 420,840 |
| 280 | 360 | 836 | 526,680 |
| 280 | 360 | 837 | 234,360 |
| 280 | 360 | 838 | 1,055,880 |
| 280 | 360 | 839 | 2,114,280 |
| 280 | 360 | 840 | 2,520 |
| 280 | 360 | 841 | 2,119,320 |
| 280 | 360 | 842 | 1,060,920 |
| 280 | 360 | 843 | 708,120 |
| 280 | 360 | 844 | 531,720 |
| 280 | 360 | 845 | 425,880 |
| 280 | 360 | 846 | 118,440 |
| 280 | 360 | 847 | 304,920 |
| 280 | 360 | 848 | 267,120 |
| 280 | 360 | 849 | 713,160 |
| 280 | 360 | 850 | 214,200 |
| 280 | 360 | 851 | 2,144,520 |
| 280 | 360 | 852 | 178,920 |
| 280 | 360 | 853 | 2,149,560 |
| 280 | 360 | 854 | 153,720 |
About "Least Common Multiple of 3 Numbers" Calculator
The Least Common Multiple of three numbers is the smallest positive integer that all three of them divide without a remainder