LCM Calculator

Yes -- that's a classic use for LCM beyond just two numbers. Enter each fraction's denominator into a Number field, using Third Number and Fourth Number for a three- or four-fraction sum, and the resulting Least Common Multiple is the smallest denominator every fraction converts into cleanly. That beats simply multiplying all the denominators together, which works but usually leaves you simplifying a much larger fraction afterward than the LCM-based denominator would.

No — First Number and Second Number are unconditionally included in the working list regardless of their value (line 60), so Numbers Calculated stays at 2 no matter what either one is set to; it only changes when you give Third Number or Fourth Number a nonzero value, adding a third or fourth entry to the list.

No, and the swings can be dramatic rather than gradual. At the defaults (12, 18), nudging Second Number down to 16 drops the LCM to 48, but a slightly different nudge that lands on a number sharing no factors with 12, like 19, sends the LCM to 228. The size of the jump depends on whether the two numbers happen to share prime factors, not on whether Second Number went up or down, so there's no steady "raising the input raises the output" trend to state for LCM or GCD themselves.

For just two numbers, listing multiples of the larger one until you hit one that's divisible by the smaller is often faster by hand, especially with small numbers or an obvious shared factor like 2 or 5. Prime factorization earns its keep once you're combining three or four numbers at once, since tracking the highest power of each prime across every number -- what this calculator's Calculation Steps output shows -- stays organized in a way that listing out multiples doesn't scale to nearly as well.