Viet is calculating the cost of the all you can drink party now.
Koichi is very quick at calculations, though he doesn't look it.
Mom! If I do all of these calculations, instead of becoming a math genius, I’ll just lose my mind.
When you measure and then calculate something, you are making a calculation. For example, you measure the length of a frog, then you calculate how many frogs you'd need to reach the moon. What is that? A calculation, of course.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.