LN in SoftMaker PlanMaker 2026: natural logarithm with worked examples

The natural logarithm solves the equation e^y = x for the exponent y: LN(x) = y. It is useful for continuously compounded change, estimating the number of periods for multiplicative growth, comparing positive ratios, and working backwards from exponential equations. The vendor describes LN as the inverse of EXP and separately documents LOG for a chosen base and LOG10 for base 10. Do not substitute LN for base-10 LOG unless you intentionally change the calculation. Source: PlanMaker 2026 LN, checked 2026-10-13.

=LN(Number)

There is one required argument and no optional second argument in the English PlanMaker 2026 and 2024 references; therefore LN has no base/default argument to configure. For instance, to take the logarithm to base 2, use the separately documented LOG(Number,2) rather than LN(Number,2). Both PlanMaker 2026 and PlanMaker 2024 give the same syntax and positive-input rule (independently checked 2026-10-13). The English reference calls this function LN and does not document a separate English alias.

Enter an = before the function in a worksheet cell: PlanMaker’s formula-entry guidance explicitly requires this. The examples below use decimal points and English-language function names. PlanMaker’s Edit settings state that decimal/thousands separators can follow the system’s region or custom preferences, and SoftMaker documents translated function names in other UI languages. Since LN accepts just one argument, a list separator is irrelevant to its own signature, but other combined functions in formulas may require localized separators. Locale variants were not run.

Create columns A and B. Put Input Number in A1 and Natural log in B1. Enter the numbers shown in A2:A9 as numbers, and put =LN(A2) in B2, copying it down to B9. Format B2:B9 to 10 decimal places if you want to see the differences, recognizing that formatting is not a change in the calculation.

Interpretation: a result may be negative even though its input must be positive. For 0 < Number < 1, natural logarithms are negative; LN(1)=0; for Number > 1, they are positive. This is a mathematical property. SoftMaker’s actual worked example LN(0.7) gives approximately −0.3567. Vendor LN. All more precise displayed results above are independent floating-point calculations, not recorded PlanMaker outputs.

Single-cell checks and inversion

• =LN(1) → independently 0.
• =LN(EXP(1.234)) → independently 1.234, matching SoftMaker’s example LN ↔ EXP.
• =EXP(LN(0.1234)) → independently 0.1234, matching SoftMaker’s EXP reference; the inner LN input is positive.
• =LN(100)/LN(10) → independently 2, using the change-of-base identity, but if you just want base 10, =LOG(100) expresses that more directly LOG.
• =LN(8)/LN(2) → independently 3, while =LOG(8,2) is a more direct formula when using a known alternate base LOG.

A constant 8% growth per period multiplies a balance by 1.08 each period. In a clean section of the same worksheet, enter A12=5000 (start), B12=10000 (goal), C12=1.08 (growth multiplier), then D12:

=LN(B12/A12)/LN(C12)

Independent expected result: approximately 9.0064683420 periods. Algebra: goal = start * multiplier^n, so n = LN(goal/start) / LN(multiplier). Both ratios and logarithm inputs are positive in this example, and the multiplier is not 1. For complete discrete periods, use an appropriate rounding-up policy independently; the formula above deliberately returns the fractional crossing time. If your input is the percentage 8% rather than the multiplier 1.08, use 1+C12 as the multiplier. This growth model and result are independent mathematics, not a SoftMaker example. Only LN syntax is attributed to the vendor LN.

Enter A15=1200 (initial), B15=1500 (ending), C15=4 (years), then D15:

=LN(B15/A15)/C15

Independent expected rate: 0.0557858878 per year, i.e. 5.578589% continuously compounded annual rate. The underlying equation is ending = initial * EXP(rate * time); algebra isolates the rate. Confirm the time units: a yearly rate requires C15 in years. Rates can be negative for declines while both monetary values must be positive to keep the ratio within LN’s documented real-number domain. This is a calculation pattern rather than a financial recommendation. LN; EXP.

If A18=25 (reference) and B18=100 (measured positive value), enter =LN(B18/A18) in C18. The independent expected log-ratio is 1.3862943611, meaning the value is a factor of 4 above reference. =LN(B18)-LN(A18) is mathematically equal but involves two logarithms and may show tiny numeric differences because of floating-point rounding. Make the ratio dimensionless by ensuring the reference and observed amounts have the same units. Never pass a negative measured difference directly as Number: LN acts on a positive ratio, not on a signed raw difference. Vendor domain requirement; algebra independently derived.

Edition, platform, language and Excel compatibility

PlanMaker 2026 (English manual): LN is documented with the exact syntax LN(Number) and Number > 0. PlanMaker 2024 (English manual): the same signature, domain and inverse EXP relationship are documented independently. Both vendor pages were accessed 2026-10-13; this does not identify a first-introduced version, prove identical Android/iOS or edition-specific behaviour, or establish a native execution test. 2026 LN; 2024 LN.

Regional formulas: SoftMaker explains localized function names and regional decimal settings. These guide examples are English/manual syntax; they are not a tested map of every translated function name or separator.

Microsoft Excel, separately documented: Microsoft’s LN guide documents LN(number) with a required positive number and identifies EXP as its inverse. This is documentation-level alignment of function names and mathematics only. No .xlsx import/export, result equality, error-code equivalence, or format round-trip test was performed, so those outcomes remain unverified.

• SoftMaker PlanMaker 2026 — LN: source of the exact signature, positive input rule and inverse example.
• SoftMaker PlanMaker 2024 — LN: independently checked historical product-manual syntax; not a date of introduction.
• SoftMaker PlanMaker 2026 — EXP: documented inverse relation and base e power.
• SoftMaker PlanMaker 2026 — LOG and LOG10: distinct logarithm bases.
• SoftMaker — entering formulas; settings, Edit tab; localized function names: user input and locale context.
• Microsoft Excel — LN: separate application reference; not PlanMaker test evidence.

Reference-check date: 2026-10-13. All PlanMaker-specific behaviours asserted as vendor facts are from the PlanMaker 2026 and 2024 English documentation cited next to their claims. Independently calculated numbers and algebraic growth models are explicitly distinguished. Native PlanMaker 2026/2024 executions: 0; Excel executions: 0; cross-format imports/exports: 0; native screenshots: 0.