Math 2 Lesson: 31 – 5
1.1. Knowledge to remember
Set the calculation and then calculate: 31 – 5
1 cannot subtract 5, take 11 minus 5 equals 6, write 6, remember 1.
3 minus 1 equals 2, write 2
So 31 – 5 = 26
1.2. Math forms
Form 1: Calculate
– Set alignment.
– Perform subtraction in turn from right to left, when the unit row of the number being subtracted is not enough to subtract, you need to perform the subtraction with memory.
Form 2: Build the math and find the result.
– Write calculations according to the data of the given problem.
– Perform calculations to find the value of the result.
Form 3: Math Quiz
– Read and analyze the topic
– Find the solution of the problem: Pay attention to the problem with the keyword “reduce”; “remaining”… then I usually use subtraction to find the solution.
– Presentation of the problem.
– Check the solution and the results you just found.
1.3. Solving Textbook Exercises
Perform subtraction of numbers from right to left.
Set the calculation and then calculate the difference, knowing the subtracted and subtracted numbers are:
a) 51 and 4; b) 21 and 6; c) 71 and 8.
– Set calculation: Write the calculation so that the digits are in the same row and column together.
– Calculation: Subtract numbers from right to left in turn.
The chickens laid 51 eggs, the mother took 6 eggs to make food. How many eggs are left?
To find the number of eggs left, subtract the number of eggs from the original number of eggs that have been eaten.
The number of eggs left is:
51 – 6 = 45 (egg)
Answer: 45 eggs.
At what point does line segment AB intersect line segment CD?
Observe the image and then find the intersection of the two lines.
(At any point where two line segments intersect, that point is called intersection)
Line segment AB intersects line segment CD at point O.