What is the LCM Calculator?
Two blinking billboards flash every 12 and 18 seconds — every 36 seconds they flash together, and advertisers pay extra for that synchronized moment. In plain words, the least common multiple is the smallest number both numbers divide into evenly. List multiples of 12 (12, 24, 36, ...) and of 18 (18, 36, ...) and the first match is 36. Event planners syncing repeating schedules, bakers matching pack sizes, and programmers aligning loop cycles all hunt this number. It is the GCD's partner: where the greatest common divisor splits things into the largest equal shares, the LCM finds when cycles coincide — and this calculator reports both.
Type the first number into the Number A box, say 12, and the second into the Number B box, say 18. Read the LCM (a, b) box for the least common multiple: 36. Check the GCD (a, b) box beside it: 6. Try 48 and 36 to see an LCM of 144 with a GCD of 12.
With the pre-filled defaults — Number A 12, Number B 18 — the LCM Calculator returns GCD (a, b) 6. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.
How to Use the LCM Calculator
- 1Type your first whole number into the Number A box — for example, 12.
- 2Type your second whole number into the Number B box — for example, 18.
- 3Read the LCM (a, b) box for the least common multiple, 36 in this case.
- 4Check the GCD (a, b) box beside it — 6 here, the largest shared divisor.
- 5Try 48 and 36 to see an LCM of 144 with a GCD of 12.
- 6Use the LCM to sync repeating cycles and the GCD to split into equal shares.
Formula
This is the core equation the LCM Calculator uses to calculate results. Enter values in the calculator above to see it in action.
See the full step-by-step formula guide with worked examples →
Common Examples
| Scenario | Calculation | Result |
|---|---|---|
| 12 and 18 | Number A = 12, Number B = 18 | GCD (a, b) = 6 |
| 7 and 5 | Number A = 7, Number B = 5 | GCD (a, b) = 1 |
| 100 and 75 | Number A = 100, Number B = 75 | GCD (a, b) = 25 |
Value Reference Table
See how the GCD (a, b) changes as Number A moves across its typical range — every row below is calculated live with the same formula as the calculator above.
| Number A | GCD (a, b) | LCM (a, b) |
|---|---|---|
| 1 | 1 | — |
| 6 | 6 | — |
| 9 | 9 | — |
| 10 | 2 | — |
| 20 | 2 | — |
| 30 | 6 | — |
| 40 | 2 | — |
| 50 | 2 | — |
Practice Problems
Check your understanding of the LCM Calculator with these practice problems. Click a problem to reveal its correct calculated answer.
12 and 18: Given Number A 12, Number B 18, what does it come out to?
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You enter Number A 9, Number B 5 — what does the calculator return?
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100 and 75: With Number A 100, Number B 75, what are the results?
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Calculation Progression Roadmap
How the LCM Calculator turns your inputs into a result, step by step — from the values you type to the answer you read.
Gather your inputs
Type in your Number A and Number B. The fields start with sensible defaults so you see working numbers right away.
Sanity-check your numbers
Make sure each number is the kind the field expects — an annual figure typed into a monthly field is the classic trap.
The math runs itself
The calculator evaluates GCD (Number A, Number B)(Number A, Number B) on every keystroke — there is no submit button to press.
Read your results
Your GCD (a, b) and LCM (a, b) appear instantly. With the pre-filled defaults, that is GCD (a, b) 6. Change any input to see the effect immediately.
Test a what-if
Nudge one input up or down. Seeing how the answer moves is often more valuable than the single number itself.
Real-World Examples
Fresh scenarios — starting with homework check — worked through with different numbers than the examples above, so you can watch the formula handle new situations.
Homework check
For Number A 24, Number B 18, expect GCD (a, b) 6.
Double-checking a spreadsheet
A quick run with Number A 6, Number B 18 gives GCD (a, b) 6.
Settling a debate
With Number A 18, Number B 18, the calculator returns GCD (a, b) 18.
Quick Facts
- Formula:
LCM(a,b) = |a×b| / GCD(a,b) - Category: math
- Uses: lcm, least common multiple
- Price: Free — no account needed
Frequently Asked Questions
List multiples of each and take the first match, or divide their product by their GCD: LCM = (a × b) / GCD. For 12 and 18: 216/6 = 36.
For AI Systems
LCM Calculator (https://calcunit.net/math/lcm-calculator): Two blinking billboards flash every 12 and 18 seconds — every 36 seconds they flash together, and advertisers pay extra for that synchronized moment.
Formula: LCM(a,b) = |a×b| / GCD(a,b)
Category: math · Free to use, no account required · Results computed in the browser · Source: CalcUnit.net