The basic four arithmetic operations (in a verb form) are almost always expressed by Native Japanese verbs. Although sometimes using the Chinese characters in wring the pronunciations remain the same, Native Japanese.
1. Addition
to add - ta-su, たす (足す), ku-wa-e-ru, くわえる （加える). The simpler ta-su, たす is commonly used. Noun form - ta-shi, たし (足し)
2. Subtraction
to subtract - hi-ku, ひく （引く). Noun form - hi-ki, ひき （引き).
3. Multiplication
to multiply - ka-ke-ru, かける (掛ける). Noun form -ka-ke, かけ (掛け)
4.Division
to divide - wa-ru, わる (割る). Noun form - wa-ri, わり (割り)
5. Equality
be equal to - (xx ni) hi-to-shi-i, (xx に) ひとしい、(等しい)
Except 1 (Addition ta-su, たすand ku-wa-e-ru) the other three 2, 3, 4 are are not only used for arithmetic used but used more universally as well.
1 + 2 = 3
In Japanese, we say ＜ichi (1) tasu ni (2) wa san (3)＞. ＜いち（１） たす に（２） は さん（３）＞.
Note: The numbers uses in arithmetic are the ones of the Chinese origin, not Native Japanese words (numbers) except ＜shi, し、4＞. ＜4＞ is usually pronounced as ＜yon, よん＞.
2. Subtraction, hi-ku, ひく has the basic meaning of ＜to draw, to pull＞and but has versatile meanings. Please refer to the follwoing post explaining hi-ku, ひく if you are familiar with written Japanese.
http://sptt-latin-subjunctive.blogspot.hk/2012/11/blog-post_11.html
3 - 2 = 1
In Japanese, we say ＜san (3) huku ni (2) wa ichi (1)＞. ＜さん（３) ひく に（２） は は いち（１）＞.
3. Multiplication, ka-ke-ru, かける also has very much versatile meanings. Please refer to the follwoing post explaining ka-ke-ru, かける if you are familiar with written Japanese.
http://sptt-latin-subjunctive.blogspot.hk/2012/11/blog-post_19.html
2 x 3 = 6
In Japanese, we say ＜ni (2) kakeru san (3) wa roku (6)＞. ＜に（２） かける さん（３) は ろく （６）＞.
4. Division, wa-ru, わる has the basic meaning of ＜to break, to cut (into pieces)＞, which easily leads to the meaning of ＜to devide＞.
4 / 2 = 2
In Japanese, we say ＜yon (4) (*) waru ni (2) wa ni (2)＞. ＜よん(4) わる に（２） は に（２）＞.
As mentioned previously yon (4) instead of shi (4) is usually used although shi (4) can be used.
－－－－
The noun forms of the above four verbs are simple, just to change the last syllable.
1. Addition： ta-su, たす (足す ーー＞ ta-shi, たし (足し)
2. Subtraction： hi-ku, ひく （引く) ーー＞ hi-ki, ひき （引き).
3. Multiplication： ka-ke-ru, かける (掛ける) ーー＞ ka-ke, かけ (掛け)
4.Division： wa-ru, わる (割る) ーー＞ wa-ri, わり (割り)
However these noun forms are not used in arithmetic but used in the daily conversations in figurative ways.
ta-shi hi-ki, たし (足し) ひき （引き) - to sum up or summing up
ka-ke hi-kii, かけ (掛け) ひき （引き) - to
wa-ri hi-ki, わり (割り) ひき （引き) ーーー＞ wa-ri bi-ki, わり (割り) びき （引き) - discount, to discount
－－－－
5. Equality
be equal to - (xx ni) hi-to-shi-i, (xx に) ひとしい、(等しい)
As shown in the above simple calculations the equality is usually expressed ＜wa（は）＞, roughly meaning ＜be＞. In a more formal arithmetic way ＜hi-to-shi-i, ひとしい＞ is used.
1 + 2 = 3
In this case we say ＜ichi (1) tasu ni (2) wa san (3) ni hitoshii＞. ＜いち（１） たす に（２） は さん（３） にひとしい＞. ＜hitoshii, ひとしい＞ is an adjective taking the helping word of＜ni, に＞ like ＜be equal to＞ in English.
＜hi-to, ひと＞ may relates with the Native Japanese number word of one (1) - ＜hi-to, ひと＞. one (1) shows identity in Multiplication and Division. a x 1 = a, b / 1 = b.
Contrast to the above simple or elementary Arithmetic, Algebra do not seem to have existed up to the introduction of the Western mathematics (some exception existed), which means there were almost no Native Japanese words for Algebra. A lot of newly coined (and still being coined) Chinese character words have been used (although a few Native Japanese are used) and its abstract nature (especially modern mathematics) the explanations of Algebra in Japanese becomes not familiar but foreign and abstract.
sptt
