Qingdao version of the mind map of addition and subtraction within ten thousand in the second volume of the second grade: 1. Convert the calculation formula into two digits + whole ten + one digit.

For example: 35+34=35+34=65+4=69. 2. Convert two-digit numbers into integer tens and one-digit numbers.

For example: 35+34=(35)+(34)=(330)+(5+4)=69.

Tip: When calculating, if the numbers in the ones place add up to ten, be sure not to forget to advance to the tens place.

1. Convert the formula to a two-digit number minus an integer to a one-digit number.

For example: 65-54=65-(54)=65-50-4=15-4=11. 2. Both the minuend and the subtrahend are converted into integers + one digit.

For example: 65-54=(65)-(54)=(60-50)+(5-4)=11. 3. For example: 65-48, because 48 is close to 50, you can start with 65-50

, then 65-48=65-(50-2)=65-52=17.

Tip: When calculating, if the number in the ones digit is not enough to decrease, move back from the tens digit.