How to cross the river on page 49 of the first grade math book?

The number that the boy above got after crossing the river was: 10.

The number the boy got after crossing the river was: 6.

The above crossing steps: 10-6=4, 4+3=7, 7-2=5, 5+4=9, 9-5=4, 4+6= 10.

The following steps are: 3+7= 10,10-5 = 5,5+2 = 7,7-6 =1,1+9= 10,/kloc-0.

Extended data

1, mixed operation sequence without brackets:

(1) If there is only addition, subtraction or multiplication and division, it should be calculated from left to right.

(2) If there are both multiplication and division and addition and subtraction, multiply and divide first, and then add and subtract.

2. The mixed operation sequence with brackets: first calculate the inside of brackets, then calculate the outside of brackets.