Kindergarten is still at the age of intellectual development, and it is difficult for children of this age to directly calculate the answer of 9+6 (unless divination). Using 6- 1 to calculate can make children's brains develop better, which is also a simple algorithm.

If children learn all kinds of simple math problem algorithms in kindergarten, it will save a lot of trouble and time in the future, and it will also help cultivate children's habit of solving math problems in various ways.

(9+ 1)+(6- 1)= 10+5= 15

Decimal system is the basic system of mathematics, which is easier for children to understand and calculate.

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