確かに[tashikani] surely
確かめる[tashikameru] to ascertain
確言[kakugen] assertion
確乎[kakko] firm
確執[kakushitsu] discord

確実[kakujitsu] certainty
確実性[kakujitsusei] certainty
確実度[kakujitsudo] certainty
確証[kakushou] positive proof
確信[kakushin] conviction

アナログ計算機[anarogukeisanki] analog computer
シフト演算機構[shifutoenzankikou] shift arithmetic unit
暗算[anzan] mental arithmetic
違算[isan] miscalculation
一般命令演算機構[ippanmeireienzankikou] general instruction unit (computer)

運算[unzan] mathematical operation
演算[enzan] (mathematical) operation
演算機[enzanki] processor (as in computer chip)
演算子[enzanshi] operator
演算手順[enzantejun] algorithm