Arithmetic — the basic school subject covering fundamental mathematics like addition, subtraction, multiplication, and division.
子どもが学校で算数を習い始めた。
My child has started learning arithmetic at school.
算数のテストで九九を覚えておくと便利だ。
It's useful to memorize the multiplication table (9x9) for arithmetic tests.
算数が得意な生徒は計算が速いことが多い。
Students who are good at arithmetic are often quick at calculations.
Calculation — the act of computing or performing numerical operations; may refer to everyday numerical calculations.
簡単な算数で家計の収支を計算した。
I calculated the household budget with simple arithmetic.
この問題は算数の基礎が分かっていれば解ける。
You can solve this problem if you understand basic arithmetic.