The elementary school subject that involves numbers can be called:
Mathematics.
The short form of this word is Math or Maths.
British English speakers normally say Maths while Americans say Math.
She loves Maths.
He hates Math.
He prepared to study Mathematics.
It is also common to say Numeracy in the U.K in primary school.
He liked Numeracy the best.
Numeracy was his favourite subject.
I hope that helps!
小学校の数字に関連する[教科](https://eikaiwa.dmm.com/uknow/questions/37923/)は、Mathematicsと言います。
短縮形は、「Math」や「Maths」という言葉です。
イギリス英語話者は、一般的に「Maths」といい、アメリカ英語話者は「Math」と言います。
She loves Maths.
彼女は算数が[大好き](https://eikaiwa.dmm.com/uknow/questions/60426/)です。
He hates Math.
彼は算数が嫌いです。
My math teacher was really mean.
私の算数の先生はとても意地悪でした。
He prepared to study Mathematics.
彼は算数を勉強する準備をしました。
イギリス人の小学校では「Numeracy」ということが普通です。
He liked Numeracy the best.
彼は算数が一番好きでした。
Numeracy was his favourite subject.
算数は彼のお気に入りの教科でした。
In the UK, we call it 'Maths' because it is an abbreviation for 'Mathematics'.
It has an 'S' on the end in both cases because when leaning the subject there are many aspects to learn.
However, Americans in their great wisdom, prefer to call the subject 'Math.'
A branch of maths is 'Arithmetic,' and this is concerned with numerical calculations, such as addition, subtraction, multiplication, and division so in elementary school, most lessons may be devoted to Arithmetic rather than the wider subject area of Maths.
Mathematics is the subject that involves numbers. In short it can be called Maths.
Example sentences.
She is very good in Mathematics.
He got an A in Mathematics.
Mathmaticsとは、数を含む教科のことです。省略してMathsと呼ばれています。
例文：
She is very good in Mathematics.
彼女は、算数がすごく得意だ。
He got an A in Mathematics.
彼は、算数でAを取った。
Most people in the United States just call this class "math", while the full word is "mathematics". In elementary classes, you will learn basic math such as counting, addition, subtraction, multiplication, and division. In more advanced math classes, students will learn subjects such as algebra, geometry, and other more complicated classes.
The full word is mathematics but it is most often shortened to just maths. Maths includes calculations such as arithmetic, subtraction, division, and multiplication.
「算数」はアメリカ英語とイギリス英語で言い方が少し違います。
アメリカ英語では算数は「math」と言います。
イギリス英語では算数は「maths」と言います。
【例】
My favorite subject is math.
→好きな教科は算数です。
Math is my favorite subject.
→算数は私の大好きな教科です。
I hated math when I was a kid.
→子どもの頃算数は嫌いでした。
ご質問ありがとうございました。
I was never very good at Maths at school...I was too arty ;-)
Americans would say MATH, while we speakers of" British English", would always say “MATHS”...Also , a generic description is often used IE, Arithmetic ;-)
Once again there are minor variations between.."Queens English"
and the USA derivations!
It is called "Mathematics."
A shorter word would be "Maths."
Examples :
She is brilliant in Mathematics.
He got an A for Maths.
She struggles with Mathematics.
He hates Maths.
これは"Mathematics"（数学 / 算数）と言います。
省略して"Maths"と言えます。
例文
She is brilliant in Mathematics.
（彼女は数学が素晴らしい）
He got an A for Maths.
（彼は数学でAを取りました）
She struggles with Mathematics.
（彼女は数学が苦手です）
He hates Maths.
（彼は数学が大嫌いです）
本当の名前はMathmaticsなんだけど日常会話の時にMath(アメリカで)かMaths(イギリスとオーストラリア)でいいです。アメリカで小学生の時にいつもMathを使いました。
I am good at math!
私は算数がよくできます！
他の皆さんがArithmeticというのはあってますがあんまり言わないです。昔にThe three Rs (三つのR)があって大丈夫にしてたんだけど見るとへんだと思いますよ。
The three Rs are "Reading", "Writing", and "Arithmetic"
三つのRは「読書」（リーディング）「作文」（ライティング）と「算数」（アリスマティック）。
全部「R」の発音が入ってますから三つのRでした。でも最近三つのRも言わないですからArithmeticはあんまり聞かないんです。
ご質問ありがとうございました！
the most common word used to name this in English is "mathematics" but you can call it "maths" for short.
example sentences: "at school my favorite subject is mathematics."
"Mathematics" is the subject in school or university where you learn about the relationship and calculations of numbers, referred to as "Math" this abbreviation of mathematics is more commonly used among people as it is easier to say and to write.
"I'd like to apply for Mathematics at Your university next year".
"I have Math for my next subject in school today".
イギリス 
南アフリカ 
日本 
アメリカ合衆国 
ニュージーランド 
