數學在中國古代把數學叫算術，又稱算學，最後才改為數學。數學分為兩部分，壹部分是幾何，另壹部分是代數。以下是我整理的關於20以內加減法口算題，希望大家認真閱讀!
14+6= 15+1= 15+2= 15+3=
15+4= 12+6= 20-0= 14-3=
14-2= 16+1= 16+2= 17-0=
11+3= 16+4= 17+1= 17+2=
18+1= 19+1= 20+0= 12+1=
3+14= 19-1= 19-2= 19-3=
11+1= 19-6= 11+6= 19-9=
11+3= 18-2= 18-6= 17-1=
13+3= 17-2= 10+6= 17-3=
17-7= 13+6= 16-1= 12+3= 16-2=
12+8= 13+4= 15-4= 13+2=
13+1= 15-1= 14+2= 12+5=
13+5= 13-1= 15-5= 14-1=
12-1= 11-1= 16-0= 13-3=
18+2= 17-6= 14+6= 15+1=
15+3= 19-0= 15+4= 11+9=
18-8= 12+4= 13-2= 12+5=
16-5= 17-1= 11+4= 13+3=
10+6= 17-3= 14+1= 17-7=
14+1= 12-2= 14+2= 16-4= 14+3=
15-7= 14-6= 11-5= 16-9= 11-8= 13-7= 15-6= 12-5= 13-9=
11-2= 13-8= 14-7= 11-3=
12-6= 14-5=
11-9= 12-8= 16-7= 13-6= 15-8=
14-9= 18-9= 12-3= 17-9= 11-4= 15-8= 12-4= 11-2= 14-6= 13-4=
12-5= 13-8= 15-6= 16-9= 14-6= 15-8= 17-10=
15-6= 16-7= 17-8= 14-5= 13-7= 14-8= 12-7= 20-10=
11-5= 12-6= 13-10= 12-7= 11-5= 13-8=
12-3= 16-8= 12-4= 17-8= 11-9= 16-7=
11-3= 17-8= 11-2= 12-8= 11-9= 13-5=
12-9= 11-5= 17-8= 16-7= 13-6 = 12-3=
16-8= 12-3= 17-9= 11-2= 17-8= 14-6=
15-7= 11-6= 12-7= 12-8= 16-8= 14-7 = 12-8 = 13-4=
15-7= 14-10= 13-8= 11-3= 14-9= 11-8= 14-7= 15-9=
19-8= 15-9= 14-5= 12-4= 16-9= 15-8= 14-7= 13-5=
11-4= 16-8= 15-6= 12-5= 14-9= 13-4= 12-8=
15-9= 12-6= 11-5= 16-7= 11-8= 14-8= 12-3= 15-7=
11-5= 12-7= 14-8= 11-6= 18-9= 16-7= 11-2=
11-4= 17-9= 20-5= 15-9= 14-6= 17-8= 13-7= 11-3=
12-7= 11-2= 15-9= 12-4= 13-9= 14-8= 18-9=
12-7= 14-6= 17-9= 13-7= 12-4= 16-7= 11-8= 14-6=
17-8= 13-9= 12-4= 11-3= 15-8= 12-9= 20-3=
11-3= 17-9= 12-6= 17-9= 12-7= 15-6= 11-7= 15-8=
11-2= 13-9= 17-8= 15-9= 11-6= 13-9= 11-3=
13-5= 18-9= 14-8= 11-6= 12-8= 15-6= 11-3= 14-5=
11-8= 12-7= 14-5 = 15-8= 11-7= 17-9= 13-8= ;