The English verb "to think" might be most synonymous with the Russian verb "думать." In English, "to think" is often used synonymously with the verb "to believe." Compare "I think you are correct" with "I believe your are correct." As for "reckoning," I have thought some about this verb. It is true that to an English speaker, "I reckon" is used most often as a colloquialism. In a more formal setting, however, the word "reckoning" has shades of both "judgment" and "calculation" in its meaning. Other synonyms might include "to consider," "to determine," "to figure," or even "to estimate." For example, there is the navigational technique of "dead reckoning" for calculating, judging, determining, or estimating one's position at sea. There is also the phrase mentioned earlier "the day of reckoning" or "judgment day" when god decides, figures out, calculates, judges, or determines who is fit for salvation and who isn't. One may also compare the word "reckon" with the German word "rechnung": a calculation, or a means of calculation. I believe then that the verb "to reckon" might be considered similar to the Russian verb "считать": to count, calculate, or consider. Hence, the meanings of "thinking" and "reckoning" intersect where one "judges," "estimates," "determines," or "figures" something to be true or untrue.