Mom bought 18 steamed stuffed bun and ate the remaining half. We need to find out how many steamed buns mom ate. Suppose mom bought 18 steamed buns at first, ate half of them, and left y steamed buns.

According to the topic, we can establish the following equation.

1. There were 18 steamed buns at first.

2. Mom ate the remaining half, that is, y/2 steamed stuffed bun.

3. The remaining Y steamed buns are expressed by a mathematical equation, which can be expressed as

1. 18-(y/2)=y

Because y is the number of steamed buns left, there are 18 steamed buns at the beginning, and the steamed buns eaten are equal to the remaining steamed buns.

Now we need to solve this equation and find the value of y.

The calculation result is: ty: 12. So, my mother ate six steamed buns.

Mathematical algorithm:

1, subtraction plus difference method

Example: 32 1-98=223 calculation method: subtract 100 and add 2.

8 135-878=7257 Calculation method: subtract 1000 and add 122.

9 132 1-8987=82334 calculation method: subtract 10000 and add 10 13.

Summary: Minus the minuend from the integer of the minuend, plus the difference between the minuend and the integer, equals the difference.

2. Find the difference between two numbers whose positions are reversed.

Example: 74-47=27 Calculation method: (7-4)x9=27.

83-38=45 Calculation method: (8-3)x9=45.

92-29=63 Calculation method: (9-2)x9=63.

Summary: the ten digits of the minuend MINUS its single digits multiplied by 9 equals the difference.

3. Find the difference between two three-digit numbers with the same middle number, but the head and tail are transposed.

Example: 936-639=297 Calculation method: (9-6)x9=27 Attention! 9 must be added to the middle of 27, which is the difference of 297.

723-327=396 Calculation method: (7-3)x9=36 Attention! 9 must be added in the middle of 36, which is the difference of 396.

873-378=495 Calculation method: (8-3)x9=45 Attention! 9 must be added in the middle of 45, which is the difference of 495.

Summary: Subtract the hundredth minuend and multiply it by 9. (9 must be written in the middle of the difference) equals the difference.

4. Find the difference between two remainders

Example: 73-27=46 Calculation method: (73-50)x2=46

6 13-387=226 calculation method: (6 13-500)x2=226.

8112-1888 = 6224 calculation method: (8112-5000) x2 = 6224.