plural of ded reckoning

The judgement, in the end times, when one is judged and punished for ones actions

Alternative spelling of ready reckoner

(historical) A very early mechanical calculator (completed in 1694) invented by Gottfried Wilhelm Leibniz.

plural of stepped reckoner

(now idiomatic, rare) To calculate one's bill without checking with the host or landlord; hence, to come to false conclusions, to miscalculate.

Borrowed money should be paid back as soon as possible.