1+3+5+7+9+12+9+7+5+3+1=;
1+3+5+7+9+11﹣6=.
3× = ﹣ = × = ÷ =
÷7= 0.5× = 12÷ = 1÷25%=
19×20%= × + × =
① +
② ×5×
③73×
④( + + )×24
⑤6.3× +3.6×0.8
⑥ ÷[1﹣ ]