1+ 1=2

1+2=3,2+2=4

1+3=4,2+3=5,3+3=6

1+4=5,2+4=6,3+4=7,4+4=8

1+5=6,2+5=7,3+5=8,4+5=9,5+5= 10

1+6=7,2+6=8,3+6=9,4+6= 10,5+6= 1 1,6+6= 12

1+7=8,2+7=9,3+7= 10,4+7= 1 1,5+7= 12,6+7= 13,7+7= 14

1+8=9,2+8= 10,3+8= 1 1,4+8= 12,5+8= 13,6+8= 14,7+8= 15,8+8= 16

1+9= 10,2+9= 1 1,3+9= 12,4+9= 13,5+9= 14,6+9= 15,7+9= 16,8+9= 17,9+9= 18

1+ 10= 1 1,2+ 10= 12,3+ 10= 13,4+ 10= 14,5+ 10= 15, 6+ 10= 16,7+ 10= 17,8+ 10= 18,9+ 10= 19

10+ 10=20

Second, the primary school mathematics subtraction formula:

9-9=0,9-8= 1,9-7=2,9-6=3,9-5=4,9-4=5,9-3=6,9-2=7,9- 1=8

8-8=0,8-7= 1,8-6=2,8-5=3,8-4=4,8-3=5,8-2=6,8- 1=7

7-7=0,7-6= 1,7-5=2,7-4=3,7-3=4,7-2=5,7- 1=6

6-6=0,6-5= 1,6-4=2,6-3=3,6-2=4,6- 1=5

5-5=0,5-4= 1,5-3=2,5-2= 1,5- 1=4

4-4=0,4-3= 1,4-2=2,4- 1=3

3-3=0,3-2= 1,3- 1=2

2-2=0,2- 1= 1

1- 1=0

Related content:

Subtraction follows several important patterns. It is anti-commutative, which means that changing the order will change the sign of the answer. It is not associative law, that is, when a subtraction exceeds two numbers, the order of subtraction is very important. Subtracting 0 does not change a number.

Subtraction also follows predictable rules related to addition and multiplication. These laws can be proved, starting with the subtraction of integers and summarizing them with real numbers and other things. Continue the general binary operation of these patterns and learn in abstract algebra.