## Overview

I have a new digital watch that's off by 40sec in 3 days. cr2025 battery is supposed to last 10 years

## watch off-by x, extend to y

## the math (requires firefox))

$\mathrm{secondsOffInXYears}=\frac{\mathrm{offBySeconds}}{\left(\left(\mathrm{daysElapsedForOffBy}\times 24\times 60\times 60\right)\times \mathrm{yearsToExtendTo}\times 365.24224\times 24\times 60\times 60\right)}$