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Prep 2 SS · Mathematics
Numbers · Real numbers

Scientific Notation

Before you start, make sure you know: Properties of exponents (High School Year 1 (semesters 1 and 2))
Before you start, make sure you know: Scientific notation (Secondary Year 3)

A human hair is about $0.000\,08$ m thick and Mexico's GDP is around $30$ trillion pesos. How can you write numbers this small or this large without getting lost in the zeros? With scientific notation.

Mantissa and order of magnitude

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The video of a well-known Mexican streamer has reached $45,200,000$ views in just one week. Express this number of views in scientific notation and state its mantissa…

The video of a well-known Mexican streamer has reached $45,200,000$ views in just one week. Express this number of views in scientific notation and state its mantissa and its order of magnitude.

Solve
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In the biology laboratory, a group of students observes that the diameter of a red blood cell is approximately $7.5 \times 10^{-6}$ meters. Express this measurement in…

In the biology laboratory, a group of students observes that the diameter of a red blood cell is approximately $7.5 \times 10^{-6}$ meters. Express this measurement in decimal form (ordinary number notation) and explain in which direction the decimal point moves and by how many places.

7.5 · 10⁻⁶ m 0 0 0 0 0 0 7 5 , , ← 6 places
Solve

Converting between decimal and scientific form

Examples of conversion to scientific notation: a large number (views of a video) and a small one, shifting the decimal point. 45,200,000 views = 4.52 · 10⁷ the point moves 7 places to the left 0.000042 = 4.2 · 10⁻⁵ (5 places to the right)
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State which of the following numbers are correctly written in standard form. If any are not, briefly explain why: a) $0.45 \times 10^{8}$ b) $1.02 \times 10^{-5}$ c)…

State which of the following numbers are correctly written in standard form. If any are not, briefly explain why:

  1. a) $0.45 \times 10^{8}$
  2. b) $1.02 \times 10^{-5}$
  3. c) $12.5 \times 10^{3}$
  4. d) $9.99 \times 10^{12}$
Solve
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Determine the value of $x$ in each of the following equations so that equivalence in standard form is maintained: a) $345,000 = 3.45 \times 10^{x}$ b)…

Determine the value of $x$ in each of the following equations so that equivalence in standard form is maintained:

  1. a) $345,000 = 3.45 \times 10^{x}$
  2. b) $0.00007 = 7 \times 10^{x}$
  3. c) $12.5 \times 10^{4} = 1.25 \times 10^{x}$
Solve
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Look at the following diagram representing the movement of the decimal point to convert the number $0.000042$ to standard form. Complete the boxes with the value of the…

Look at the following diagram representing the movement of the decimal point to convert the number $0.000042$ to standard form. Complete the boxes with the value of the coefficient (mantissa) and the corresponding exponent.

0 . 0 0 0 0 4 . 2 1 2 3 4 5 mantissa · 10 exponent
Solve
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In microelectronics, the thickness of an insulating layer in a processor is $4.5$ nanometers ($1 \text{ nm} = 10^{-9} \text{ m}$). If the processor has a total surface…

In microelectronics, the thickness of an insulating layer in a processor is $4.5$ nanometers ($1 \text{ nm} = 10^{-9} \text{ m}$). If the processor has a total surface area of $1.2 \text{ cm}^2$:

  1. a) Express the thickness of the layer in meters using scientific notation.
  1. b) Calculate the total volume of insulating material used in that processor in cubic meters ($m^3$). Take into account that the volume is the product of the surface area and the thickness.
Solve

Comparing numbers in scientific notation

Number line with a scale of powers of 10 that locates two quantities according to their order of magnitude. 4.7·10⁷ 1.4·10⁹ 10⁴10⁶10⁸10¹⁰ scale of powers of 10: each mark = ×100
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A technology company is comparing the size of three electronic components. The sizes are: $A = 3.2 \times 10^{-4}$ mm, $B = 1.5 \times 10^{-3}$ mm and…

A technology company is comparing the size of three electronic components. The sizes are: $A = 3.2 \times 10^{-4}$ mm, $B = 1.5 \times 10^{-3}$ mm and $C = 8.9 \times 10^{-4}$ mm. Order the components from smallest to largest based on their exponents and mantissas.

Solve

Operating in scientific notation

Diagram of the product in scientific notation: the mantissas are multiplied, the exponents are added, and the result is adjusted to standard form. 3 · 10⁹ · 5 · 10⁻³ = 15 · 10⁶ = 1.5 · 10⁷ mantissas: are multiplied powers: the exponents are added

Multiplying and dividing: you operate on the mantissas and the powers of $10$ separately (the exponents are added when multiplying and subtracted when dividing). At the end you adjust the mantissa if it falls outside $[1, 10)$. Adding and subtracting: you must make the exponents equal first.

Roots of numbers in scientific notation

A root is a power with a fractional exponent: $\sqrt{10^{n}} = 10^{n/2}$ and $\sqrt[3]{10^{n}} = 10^{n/3}$. That is why it helps to rewrite the number so that the exponent of $10$ is a multiple of the index (even for the square root, a multiple of $3$ for the cube root). You take the root of the mantissa and of the exponent separately.

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The mean distance from the Earth to the Sun is approximately $1.5 \times 10^{8}$ km. If light travels at a speed of $3 \times 10^{5}$ km/s, calculate the time it takes…

The mean distance from the Earth to the Sun is approximately $1.5 \times 10^{8}$ km. If light travels at a speed of $3 \times 10^{5}$ km/s, calculate the time it takes for sunlight to reach the Earth, carrying out the operation directly in standard form (remember that $t = \frac{d}{v}$).

d = 1.5 · 10⁸ km Sun Earth v = 3 · 10⁵ km/s t = ?
Solve
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A data server stores music files. Each song occupies an average of $4.5 \times 10^{6}$ bytes. If the server has $2 \times 10^{4}$ songs stored, how many total bytes of…

A data server stores music files. Each song occupies an average of $4.5 \times 10^{6}$ bytes. If the server has $2 \times 10^{4}$ songs stored, how many total bytes of music are on the server? Express the final result in standard form.

Solve
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Carry out the following combined operations and express the result in standard form, rounding to three significant figures: $$\frac{(3.42 \times 10^5) \times (2.8 \times…

Carry out the following combined operations and express the result in standard form, rounding to three significant figures:

$$\frac{(3.42 \times 10^5) \times (2.8 \times 10^{-8})}{1.2 \times 10^{-4} + 5.6 \times 10^{-5}}$$
Solve
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Calculate the value of the following expression, simplifying the result as far as possible, and express it in standard form to three significant figures: $$L =…

Calculate the value of the following expression, simplifying the result as far as possible, and express it in standard form to three significant figures:

$$L = \frac{(3.2 \times 10^{-5} + 1.8 \times 10^{-6})^2}{\sqrt{1.44 \times 10^{-18}}} \times \sqrt[3]{8 \times 10^{12}}$$

Next, bound the absolute error made when rounding the value of $L$ to the first decimal place of its mantissa.

Solve

Units and significant figures

Many problems ask you to change units (MB to GB, nm to m, cm² to m²) and to give the result with a certain number of significant figures: the digits of the mantissa. So, $4.25\times10^{-22}$ has three significant figures.

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In a data processing center of a well-known social network, it is estimated that $2.5 \times 10^6$ megabytes (MB) of new information are generated every second. a)…

In a data processing center of a well-known social network, it is estimated that $2.5 \times 10^6$ megabytes (MB) of new information are generated every second.

  1. a) Express in scientific notation how many gigabytes (GB) are generated in a full day (assume $1 \text{ GB} = 10^3 \text{ MB}$).
  1. b) If each storage hard drive has a capacity of $1.2 \times 10^{13}$ bytes, how many hard drives would be needed to store the information of a leap year? (assume $1 \text{ MB} = 10^6 \text{ bytes}$). Give the result to three significant figures.
Solve
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The mass of a suspended dust particle is approximately $7.25 \times 10^{-10}$ kg. After one week of operation, an air purifier has captured a total of…

The mass of a suspended dust particle is approximately $7.25 \times 10^{-10}$ kg. After one week of operation, an air purifier has captured a total of $4.35 \times 10^{-2}$ grams of these particles.

  1. a) Calculate the total number of particles captured by the purifier.
  1. b) If the purifier filter must be changed when it reaches an accumulated mass of $1.5 \text{ decigramos}$, how many more weeks can it operate before requiring maintenance? Express the calculations and the final result in standard form.
Solve

Absolute and relative error

If $V$ is the true value and $A$ is the approximation:

$$\text{absolute error} = |V - A| \qquad \text{relative error} = \frac{|V - A|}{|V|}$$

The relative error is given as a percent by multiplying by $100$. The absolute error tells you how far off you were; the relative error tells you how serious that is compared to the size of what was measured.

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The mass of a laboratory object has been measured, giving a value of $3.45 \times 10^{-3}$ grams, although the true value is $3.458 \times 10^{-3}$ grams. a) Calculate…

The mass of a laboratory object has been measured, giving a value of $3.45 \times 10^{-3}$ grams, although the true value is $3.458 \times 10^{-3}$ grams.

  1. a) Calculate the absolute error made in the measurement.
  1. b) Calculate the relative error and express it as a percentage. Is it considered a precise measurement if the acceptable margin of error is $0.5\%$? Justify your answer.
Solve

Tolerances: distance from a central value

A parts factory accepts a measurement if it is not far from the ideal value. "Not far" is written with absolute value: $|x-a|$ is the distance between $x$ and $a$ on the real number line.

Real number line with the interval of center a and radius r: it goes from a minus r to a plus r. a − r a a + r r r
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Represent on the number line the set of numbers satisfying the following "industrial tolerance" condition for a precision part: $$A = \{ x \in \mathbb{R} \mid |x - 4.5…

Represent on the number line the set of numbers satisfying the following "industrial tolerance" condition for a precision part:

$$A = \{ x \in \mathbb{R} \mid |x - 4.5 \times 10^{-3}| \le 2 \times 10^{-4} \}$$
  1. a) Express the set in interval form and as an inequality without modulus.
  1. b) Is the number $0.00435$ an acceptable value for this part? Justify your answer by checking whether it belongs to the set.

You can do it on paper and send a photo with your answer.

Solve
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In a nanotechnology laboratory, the mass of a new synthetic particle is being analysed, estimated at $m = 4.25 \times 10^{-22}$ grams. However, the measuring instrument…

In a nanotechnology laboratory, the mass of a new synthetic particle is being analysed, estimated at $m = 4.25 \times 10^{-22}$ grams. However, the measuring instrument has an absolute error bound of $5 \times 10^{-25}$ grams. On the other hand, an astronomer measures the mass of a nearby asteroid as $M = 7.8 \times 10^{15}$ kilograms with a relative error of $0.01\%$.

Carry out the following tasks, expressing all results in standard form:

  1. a) Determine the interval of possible values for the mass of the particle $m$ using neighbourhood notation $E(a, r)$.
  1. b) Calculate the relative error bound made in measuring the particle and compare it with the relative error of the asteroid. Give reasons to justify which measurement is more precise.
  1. c) If $1.5 \times 10^{24}$ identical particles were combined, what would be the resulting total mass? Consider both the estimated value and the accumulated absolute error.
Solve

Applications in technology, science, and economics

Example of a quotient in scientific notation: income per person as GDP divided by population. Income per person = GDP / population GDP = 1.8·10¹² pesos · population = 6·10⁷ people = 3·10⁴ pesos per person

Growth and rates in pesos

When something grows by a rate $i$ each period, the quantity is multiplied by $(1+i)$ every period. After $n$ periods it is multiplied by $(1+i)^n$. With huge figures, scientific notation helps you keep track of the calculations.

Circumference of a circle

A circle of diameter $d$ has a circumference of length $C = \pi d = 2\pi r$, where $r$ is the radius. This is useful for red blood cells, pipes, or gears.

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A red blood cell has an approximately circular shape with a diameter of $7.5 \times 10^{-4} \text{ cm}$. a) Calculate the circumference of the cell in meters. (Use…

A red blood cell has an approximately circular shape with a diameter of $7.5 \times 10^{-4} \text{ cm}$.

  1. a) Calculate the circumference of the cell in meters. (Use $\pi \approx 3.1416$).
  1. b) If we could line up end to end all the red blood cells of an adult (approximately $2.5 \times 10^{13}$ cells), what distance in kilometers would they cover? Express the result in scientific notation.
Red blood cell d = 7.5 · 10⁻⁴ cm C = ? m Line of cells N = 2.5 · 10¹³ D = ? km
Solve
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The mean distance from the Earth to the Sun is $1.496 \times 10^8 \text{ km}$. The speed of light is $3 \times 10^8 \text{ m/s}$. a) Calculate how long, in minutes and…

The mean distance from the Earth to the Sun is $1.496 \times 10^8 \text{ km}$. The speed of light is $3 \times 10^8 \text{ m/s}$.

  1. a) Calculate how long, in minutes and seconds, it takes for sunlight to reach the Earth.
  1. b) If a spacecraft travels at a constant speed of $5.5 \times 10^4 \text{ km/h}$, how many days would it take to complete the round trip?
Solve
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A social network data center processes approximately $2.5 \times 10^6$ queries per second. Each query requires the movement of $1.2 \times 10^4$ bytes of information. a)…

A social network data center processes approximately $2.5 \times 10^6$ queries per second. Each query requires the movement of $1.2 \times 10^4$ bytes of information.

  1. a) Calculate how many terabytes ($1 \text{ TB} = 10^{12} \text{ bytes}$) of information the center processes in a leap year.
  1. b) If the center plans to increase its processing capacity by $15\%$ annually compounded, how much information (in bytes) will it process per second in a decade? Express the result in scientific notation.
Solve

Back to the beginning: the hair of $0.000\,08$ m is $8\times10^{-5}$ m and the GDP of $30$ trillion is $3\times10^{13}$ pesos. With the exponent we can compare their scales at a glance without counting zeros.

Summary

See all the exercises in this section