Mathematics In ancient China, mathematics was called arithmetic, also called arithmetic, and was finally changed to mathematics. Mathematics is divided into two parts, one is geometry and the other is algebra. The following are oral calculation questions about addition and subtraction within 20, I hope you will read them carefully!

14+6= 15+ 1= 15+2= 15+3=

15+4= 12+6= 20-0= 14-3=

14-2= 16+ 1= 16+2= 17-0=

1 1+3= 16+4= 17+ 1= 17+2=

18+ 1= 19+ 1= 20+0= 12+ 1=

3+ 14= 19- 1= 19-2= 19-3=

1 1+ 1= 19-6= 1 1+6= 19-9=

1 1+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= 1 1- 1= 16-0= 13-3=

18+2= 17-6= 14+6= 15+ 1=

15+3= 19-0= 15+4= 1 1+9=

18-8= 12+4= 13-2= 12+5=

16-5= 17- 1= 1 1+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= 1 1-5= 16-9= 1 1-8= 13-7= 15-6= 12-5= 13-9=

1 1-2= 13-8= 14-7= 1 1-3=

12-6= 14-5=

1 1-9= 12-8= 16-7= 13-6= 15-8=

14-9= 18-9= 12-3= 17-9= 1 1-4= 15-8= 12-4= 1 1-2= 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=

1 1-5= 12-6= 13- 10= 12-7= 1 1-5= 13-8=

12-3= 16-8= 12-4= 17-8= 1 1-9= 16-7=

1 1-3= 17-8= 1 1-2= 12-8= 1 1-9= 13-5=

12-9= 1 1-5= 17-8= 16-7= 13-6 = 12-3=

16-8= 12-3= 17-9= 1 1-2= 17-8= 14-6=

15-7= 1 1-6= 12-7= 12-8= 16-8= 14-7 = 12-8 = 13-4=

15-7= 14- 10= 13-8= 1 1-3= 14-9= 1 1-8= 14-7= 15-9=

19-8= 15-9= 14-5= 12-4= 16-9= 15-8= 14-7= 13-5=

1 1-4= 16-8= 15-6= 12-5= 14-9= 13-4= 12-8=

15-9= 12-6= 1 1-5= 16-7= 1 1-8= 14-8= 12-3= 15-7=

1 1-5= 12-7= 14-8= 1 1-6= 18-9= 16-7= 1 1-2=

1 1-4= 17-9= 20-5= 15-9= 14-6= 17-8= 13-7= 1 1-3=

12-7= 1 1-2= 15-9= 12-4= 13-9= 14-8= 18-9=

12-7= 14-6= 17-9= 13-7= 12-4= 16-7= 1 1-8= 14-6=

17-8= 13-9= 12-4= 1 1-3= 15-8= 12-9= 20-3=

1 1-3= 17-9= 12-6= 17-9= 12-7= 15-6= 1 1-7= 15-8=

1 1-2= 13-9= 17-8= 15-9= 1 1-6= 13-9= 1 1-3=

13-5= 18-9= 14-8= 1 1-6= 12-8= 15-6= 1 1-3= 14-5=

1 1-8= 12-7= 14-5 = 15-8= 1 1-7= 17-9= 13-8= ;