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Rational numbers can be divided into positive numbers, negative numbers and 0, or positive numbers and fractions. According to what are these two kinds of fractions? For example, by concept, by meaning and so on,
A positive number, a negative number, and a zero (positive means increase, negative means decrease, and zero means constant)
Integers and fractions in the form of it (integers are integers, fractions are decimals (except infinite non cyclic decimals))
In rational numbers, are there the largest positive number and the smallest negative number? Are there the largest negative integer and the smallest positive integer? If so, what are the numbers?
There is no maximum positive number and minimum negative number
There are the largest negative integer - 1 and the smallest positive integer 1
Is there the largest positive number and the smallest negative number in the rational number? Is there the largest negative integer and the smallest positive integer
There is no maximum positive number and minimum negative number
The largest negative integer is - 1
The smallest positive integer is 1
In rational numbers, is there the smallest negative number? Is there the largest positive number? Why?
No, because the smallest negative rational number can only be infinitely close to 0, but it will never be equal to 0, so it is not the smallest negative rational number in the strict sense. At the same time, there is no largest positive number
We should use the knowledge of the fifth grade mark addition and subtraction method, and we should use the formula to calculate
Question 1: 7 / 2-15
Question 2: 13 out of 15 + 11 out of 15
Question 1: 2-7 / 15
=1-7|15 + 1 = 8 / 15 + 1 = 1 and 8 / 15
=23/15
Question 2: 13 / 15 + 11 / 15
=（13+11）/15
=24/15
=24/ 15 =8/5
=Again and again
6 10 17 11 --- --- --- --- 23 —21 + 23 ---21
Urgent, fifth grade score addition and subtraction method,
6/23-10/21+17/23-11/21
=(6/23+17/23)-(10/21+11/21)
=1-1
=0
Find a simpler different denominator fraction addition and subtraction 300, no reduction
3/4+1/5=4/5 3/4-1/5=11/20 5/6+2/9=19/18 5/6-2/9=11/18 2/3+3/5=19/152/3-3/5=1/15 6/7+1/2=19/14 6/7-1/2=5/14 2/3+1/6=5/6 1/3+1/4=7/121/3-1/4=1/12 1/5+1/7=12/35 1/5-1/7=2/35 1/4+1/9=13/36 1/4-1/9=5/361/8...
How to add and subtract quickly
It can't be done in one day or two. Habitual mental arithmetic will speed up after a long time
A mathematical problem of defining mental arithmetic
If a * b = a + 2B, then 3 * 4 * 1 / 2
——
2b
a*b=a+2b
——
2b
Just substitute a = 3 and B = 4 into the calculation
3+2×3
3 * 4 * 1 / 2 = -- * 1 / 2
2×3
nine
= —* 1/2
six
= 3/2* 1/2
3/2+2×1/2
= ——————
2×1/2
=5/2
Why is my mathematical calculation problem OK, but my mental calculation is very poor? Who can teach me how to solve the mathematical problem of mental calculation, from simple addition and subtraction to difficult multiplication and division
Ask for advice on mathematical problems of mental arithmetic
In fact, the biggest difference between mental arithmetic and written arithmetic lies in memory. To reproduce and recombine the steps and values of written arithmetic in the brain, the test is memory and abstract thinking ability
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