Leave one box empty — it becomes the unknown
🪜 Logarit
Solve log_b(x) = y whichever way you need: fill any two of base, argument and result, the empty one is computed with steps shown. Below, a live log-scale ruler shows why the logarithm is just “how many digits”.
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The log ruler — a logarithm is “how many digits”
Log laws, with your numbers
log_b(x) answers “b to what power gives x?”. Change of base: log_b(x) = ln x / ln b — that one line is how every calculator computes any logarithm. Decibels, pH, earthquake magnitudes and musical octaves are all logarithms in disguise.