2 - 1 = 1

5 - 3 = 2

10 - 6 = 4

12 - 4 = 8

20 - 7 = 13

※　たし算　(addition)
例)　1 + 1 = 2
One plus one is two.  [One plus one equals　two.]

※　ひき算　(subtraction)
例)　2 - 1 = 1
Two minus one is one.  [Two minus one equals one.]

※　かけ算  (multiplication)
例) 2 × 3 = 6
Two multiplied by three is six. [Two multiplied by three equals six.]

※　わり算  (division)
例) 6 ÷ 3 = 2
Six divided by three is two.  [Six divided by three equals two. ]