Studying mathematics for the sake of mathematics, formulation of conjectures to model real life situations and indeed the application of mathematical knowledge has helped to improve insight about nature.

The advances in pure mathematics, natural sciences, engineering, medicine, finance and the social sciences has lead to the formulation of more practical problems requiring practical solutions. Some of these needed solutions however pose a great strain on the human numerical capacity, hence the need for calculators.

Antiquity supplied itself with a means to eliminate this strain on the human numerical capacity and indeed eliminate error in calculations. The first calculators were recognized as mere counting materials and devices; they were stones, pebbles, bones and the abacus.

It was not until the 17^{th} century that the term calculating machine or mechanical calculator became widespread. Wilhelm Schickard built the earliest modern attempt at a mechanical calculator. His mechanical calculator comprised Abacus made of Napier bones which performed multiplication and division operations and a dialed pedometer which performed addition and subtraction operations. However, he was not very successful.

The image above represents a cuboid.
To compute the area of a cuboid requires three essential parameters which are the length, width and height of the cuboid.

The formula for computing the area of a cuboid is:

A = 2(lw + lh + wh)

Where:
A = Area of the Cuboid
l = Length of the Cuboid
w = Width of the Cuboid
h = Height of the Cuboid

Let’s solve an example
Find the area of a cuboid with a length of 5 cm, width of 3 cm and a height of 9 cm.

This implies that:
l = length of the cuboid = 5
w = width of the cuboid = 3
h= = height of the cuboid = 9

A = 2(lw + lh + wh)
A = 2(5 x 3 + 5 x 9 + 3 x 9)
A = 2(87)
A = 174

Therefore, the area of the cuboid is 174 cm^{2}.

Calculating the Length of a cuboid when Area, Width and Height are Given

The formula is l = ^{A – 2(w)(h)} / _{2(w) + 2(h)}

Where;
A = Area of the Cuboid
l = Length of the Cuboid
w = Width of the Cuboid
h = Height of the Cuboid

Let’s solve an example:
Find the length of a cuboid with an area of 140 cm^{2} , a width of 4 cm and a height of 12 cm

This implies that;
A = Area of the cuboid = 140 cm^{2}
w = width of the cuboid = 4 cm
h = height of the cuboid = 12 cm

l = ^{A – 2(w)(h)} / _{2(w) + 2(h)}
l = ^{140 – 2(4)(12)} / _{2(4) + 2(12)}
l = ^{140 – 96} / _{8 + 24}
l = ^{44} / _{32}
l = 1.375 cm

Therefore, the length of the cuboid is 1.375 cm.

Calculating the Width of a cuboid when Area, Length and Height are Given

The formula is w = ^{A – 2(l)(h)} / _{2(l) + 2(h)}

Where;
A = Area of the Cuboid
l = Length of the Cuboid
w = Width of the Cuboid
h = Height of the Cuboid

Let’s solve an example:
Find the width of a cuboid with an area of 200 cm^{2} , a length of 5 cm and a height of 12 cm

This implies that;
A = Area of the cuboid = 200 cm^{2}
l = length of the cuboid = 5 cm
h = height of the cuboid = 12 cm

w = ^{A – 2(l)(h)} / _{2(l) + 2(h)}
w = ^{200 – 2(5)(12)} / _{2(5) + 2(12)}
w = ^{200 – 120} / _{10 + 24}
w = ^{80} / _{34}
w = 2.353 cm

Therefore, the width of the cuboid is 2.353 cm.

Calculating the Height of a cuboid when Area, Length and Width are Given

The formula is h = ^{A – 2(l)(w)} / _{2(l) + 2(w)}

Where;
A = Area of the Cuboid
l = Length of the Cuboid
w = Width of the Cuboid
h = Height of the Cuboid

Let’s solve an example:
Find the height of a cuboid with an area of 300 cm^{2} , a length of 6 cm and a width of 2 cm

This implies that;
A = Area of the cuboid = 300 cm^{2}
l = length of the cuboid = 6 cm
w = width of the cuboid = 2 cm

h = ^{A – 2(l)(w)} / _{2(l) + 2(w)}
h = ^{300 – 2(6)(2)} / _{2(6) + 2(2)}
h = ^{300 – 24} / _{12 + 4}
h = ^{276} / _{16}
h = 17.25 cm

Underwater research has provided guidance and opportunities for original researches to be conducted in the field of subtidal marine ecology. The research has been devoted particularly to the physiological process and limits of breathing gas under pressure, for aquanaut and astronaut training as well as for research on marine ecology.

Water quality index (WQI) is a means by which water quality data is summarized for reporting to the public in a consistent manner. It is similar to UV index or air quality index. Water quality index, as an area of activity under underwater research, is a 100-point scale that summarizes results from a total of nine different measurements when complete. These nice factors which includes:- dissolved oxygen, fecal coliform, PH, biochemical oxygen demand, temperature change, total phosphate, nitrates, turbidity and total solids, are chosen and some judged more important than the other, after which a weighted mean is used to combine the values.

The updated calculator used for this computation allows one to enter the longitude and latitude for the site under consideration or pick location from a Google earth map. The calculator completes the individual and group calculations of the aforementioned factors under consideration and permits one to generate a customized report.
The water quality index has a legend for grading range of values gotten at the final stage of each computation, which suggests the state of water falling between each range. The six widely used legends are excellent, very good, good, fair, marginal and poor.

The significant figures (also known as the significant digits) of a number are digits that carry meaning contributing to its measurement resolution. This includes all digits except:^{}

Spurious digits introduced, for example, by calculations carried out to greater precision than that of the original data, or measurements reported to a greater precision than the equipment supports.

Nickzom Calculator computes the significant figures of any given number.

For Example: apply 3 significant figures to 123876 and apply 2 significant figures to 0.00009872.

First, you need to obtain the Nickzom Calculator – The Calculator Encyclopedia app.
You can get this app via any of these means:

Once, you have obtained the calculator encyclopedia app, proceed to the Calculator Map, then click on Significant Figures under the Mathematics section

On clicking the page or activity to enter the values is displayed.

From the first example: apply 3 significant figures to 123876 It implies that the number is 123876 and the number of significant figures to apply is 3.