I can give examples of decimal addition and subtraction in my life and calculate them correctly It's urgent. I really need two

I can give examples of decimal addition and subtraction in my life and calculate them correctly It's urgent. I really need two

When you go to the market to buy fruits, you know that you have 30.2 yuan and 3.2 yuan for one kilo of oranges. If you buy eight kilos of oranges, how much money is left?
30.2-3.2x8 = 30.2-25.6 = 4.6 (yuan)

Although it's a little hard to find the examples expressed by limited decimal in life, we can make do with them
Sorry for the wrong number. It's an infinite number in life

Height: 1.65m
Price: 12.3 yuan
Track and field results: 12.91 seconds
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The concept of decimal
About 100 words, as long as the concept of decimal on the line

Decimals are composed of integral parts, decimal parts and decimal points. When measuring objects, we often get numbers that are not integers. The ancients invented decimals to supplement integers. Decimals are a special form of decimal fractions. Denominators are 10, 100, 1000 All fractions can be expressed as decimals, except infinite non cyclic decimals. Irrational numbers are infinite non cyclic decimals
According to the decimal place value principle, the decimal fraction is written in the form of integer without denominator. Such a number is called a decimal. The dot in the decimal is called the decimal point, which is the dividing mark between the integer part and the decimal part of a decimal. The part on the left of the decimal point is the integer part, and the part on the right of the decimal point is the decimal part. The decimal with the integer part zero is called a pure decimal, Decimals whose integral part is not zero are called with decimals. For example, 0.3 is pure decimals and 3.1 is with decimals

Third day of a pressure physics problem, how to do ah?
There is an object a on object B, a weighs 30n, B weighs 15N, the bottom area of object a is 10 square centimeter, and the bottom area of object B is 5 square centimeter. How about the pressure of a on B

P（A）=F/S= 30÷5×10^-3=6000 Pa

Ask a physics problem about liquid pressure in the third grade of junior high school
A plastic bottle has two small holes a and B on its side wall (point a is on point B) and is plugged with a stopper. There is a certain amount of alcohol in the bottle, as shown in the figure (the picture is not complete, but it is a big bottle of water on the outside, and a small bottle on the inside is alcohol. A and B are on the same side of the small bottle, a is on the top, B is on the bottom). Put the plastic bottle into the water. When the liquid surface of the bottle is normal, pull out the stopper at the two small holes a and B, then, a, B, B, a, B, B, a, B, B, a, B, B, a, B, B, B, B, a, B, Both of the two orifices of B have water flowing in, B water flowing in from the orifices of B, and alcohol flowing out from the orifices of a {these are two reasonable answers. The standard answer gives a, but it seems that only considering that P water is greater than p alcohol, it is not in line with the actual situation}

There is nothing unreasonable. At the moment when the plug is removed, because the internal and external liquid level is relatively flat, P = pGH. The density of water is higher than that of alcohol, so the pressure of water is high at the small hole, so water flows into the two small holes a and B

The filament of a light bulb is broken. If the broken filaments are used together, the light bulb will be (fill in "on" or "dark"), and the reason you explain is

Bright
Cause: if the disconnected filaments are put together, the filament length decreases, the cross-sectional area increases, and the resistance decreases. According to the formula: P = u & sup2 / R, u remains unchanged, R decreases, and P increases, so the bulb will turn on

The geomagnetic field on the equator can be regarded as a uniform magnetic field. A 50cm long electrified straight wire is placed perpendicular to the direction of the geomagnetic field on the equator. When the current in the wire is 30a, the ampere force on the wire is 3 × 10-2n

(1) From the formula of Ampere force F = bil, B = fil = 3 × 10 − 230 × 0.5T = 2 × 10-3t. (2) when the current in the conductor is reduced to 20a, the magnetic induction is constant. F = Bi ′ L = 2 × 10-3 × 20 × 0.5N = 2 × 10-2n; & nbsp; A: (1) the magnetic induction intensity of the geomagnetic field on the equator is 2 × 10-3t; (2) if the current in the conductor is reduced to 20a, the ampere force on the conductor is 2 × 10-2n

Use a thermometer, a small beaker, a bottle of alcohol, design an experiment, prove: alcohol evaporation process of heat absorption, please write down the experimental steps and experimental phenomena

A: pour some alcohol into the small beaker, dip some alcohol into the glass bulb of the thermometer, and then take it out. It is found that the thermometer's indication decreases, indicating that it is evaporating and absorbing heat

An object with a mass of 3kg is still on the horizontal ground. Under the action of 10N horizontal tension, it begins to make a uniform acceleration linear motion along the horizontal ground. The friction between the object and the ground is 4N. Find: (1) the speed of the object at the end of 3S. (2) the displacement of the object within 3S

According to Newton's second law, a = f − FM = 10 − 43M / S2 = 2m / S2. Then the velocity at the end of the second second second is v = at = 2 × 3m / S = 6m / s. The displacement in the first two seconds is x = 12at2 = 12 × 2 × 32 = 9m