Kindergarten numbers 1 and 9, 4 and 6 are complementary, that is, they are all added to I0, and there are also 5 and 5, 3 and 7, 1 and 9, which is the method used by kindergartens to add to 10.

For example:

If it is full, add five, and if it is broken, subtract five (the next five is rounded off, and the last five is rounded off), master the concept of making up the number (two numbers add up to five, which is called making up the number), and practice mental arithmetic on the abacus.

Carry and subtraction, master the concept of complement (two numbers add up to 10 is complementary,) abacus mental arithmetic.

Break the 5-digit addition and abdicate by 5.

Break the five-digit addition, abdicate more than five, and subtract the mental arithmetic.

Two-digit 3~5 addition and subtraction mental arithmetic

Extended data:

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

12-9=3 12-8=4 12-7=5 12-6=6 12-5=7 12-4=8 12-3=9

13-9=4 13-8=5 13-7=6 13-6=7 13-5=8 13-4=9

14-9=5 14-8=6 14-7=7 14-6=8 14-5=9

15-9=6 15-8=7 15-7=8 15-6=9

Baidu encyclopedia-abdication addition and subtraction