Number series are fundamental to algebra and calculus.
Arithmetic: aₙ = a₁ + (n−1)d.
Geometric: aₙ = a₁ × r^(n−1).
Reach for this calculator when you need a result you can act on confidently. The formula is straightforward, but manual computation introduces rounding errors that this tool eliminates entirely.
Many errors with this type of calculation stem from unit inconsistency: mixing metric and imperial, or mixing annual and monthly rates. Ensure all inputs use the same unit system before running the calculation.
A shopper sees two versions of the same product at different prices: one at £14.50 for 400g and another at £11.99 for 300g. Running both price-per-gram calculations reveals the larger pack is 7% cheaper per unit — the kind of comparison that is impossible to do reliably in your head at the shelf.
A sequence where each term differs from the previous by a constant: 2, 5, 8, 11...
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