In Hebrew: 'Calculation'

חִשּׁוּב The Hebrew root, ח.שׁ.ב (kh.sh.b) meaning thinking, produces many words, perhaps most notable among which are חָשׁוּב - important, לַחְשׁוֹב - to think - and מַחְשֵׁב - computer.

Another word that's useful in math class, in business settings and elsewhere is that for calculation - חִשּׁוּב. This word is the noun form of the active-intensive פִּעֵל verb, לְחַשֵּׁב.

For example:

.הַחוֹקֵר מַדְפִּיס אֶת כָּל הַחִשּׁוּבִים שֶׁלּוֹ בְּדַף אֶחָד The researcher is printing all of the calculations on one page. When not vocalized, the word חִשּׁוּב appears as חישוב, so it can be distinguished from the word for important - חָשׁוּב or חשוב.

As for calculator, see this entry.

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