Category: Arithmetic
"Published in Newark, California, USA"
Divisibility by 1:
How do you know that a number is divisible by 1? Well, any number divided by 1 is the same number.
Example 1:
Example 2:
Divisibility by 2:
How do you know that a number is divisible by 2? Well, a number is divisible by 2 if a number ends with 0, 2, 4, 6, and 8. In short, all even numbers are divisible by 2.
Example 1:
Since 585 is not an even number, then it is not divisible by 2. The answer or a quotient must be a whole number itself. You should not have a fraction or a remainder in the final answer.
Example 2:
Since 3006 is an even number, then it is divisible by 2. The answer or a quotient is a whole number and there's no fraction or remainder.
You should consider in studying the divisibility of a number because you will use these principles later when you will study higher Math subjects that involves the division of a number, simplifying fractions, and even factoring.
By the way, we can do the division of a number without using a calculator or even a scratch paper and a pen. Let's consider this number
Let's start with 5 (left side). 5 divided by 2 is 2. We cannot say 3 because 2 times 3 is 6. 2 times 2 is 4 and that's the highest number that we can consider. 5 minus 4 is 1 and there's a remainder of 1 from the first digit.
Next, consider the next digit which is 8. Since you have a remainder of 1 from the first digit, then 8 becomes 18. 18 divided by 2 is 9. That's good that 18 is an even number or else we will have another remainder. When you divide any odd numbers by 2, the remainder is always 1.
Finally, consider the last digit which is 5. Since the second digit has no remainder, then we can use 5 in the division. 5 divided by 2 is 2. We cannot say 3 because 2 times 3 is 6. 2 times 2 is 4 and that's the highest number that we can consider. 5 minus 4 is 1. Therefore, the final answer is 292 and has a remainder of 1. 1 is the numerator in the fraction which is the remainder and 2 is the denominator which is the divisor.
Let's consider another number
Let's start with 3. 3 divided by 2 is 1. We cannot say 2 because 2 times 2 is 4. 2 times 1 is 2 and that's the highest number that we can consider. 3 minus 2 is 1 and there's a remainder of 1 from the first digit.
Next, consider the next digit which is 0. Since you have a remainder of 1 from the first digit, then 0 becomes 10. 10 divided by 2 is 5. That's good that 10 is an even number.
Next, consider the next digit which is 0. Since there's no remainder in the second digit, then we can use 0 in the division. 0 divided by 2 is 0. Zero divided by any number (except zero) is always equal to zero.
Finally, consider the last digit which is 6. Since there's no remainder in the third digit, then we can use 6 in the division. 6 divided by 2 is 3. That's good that 6 is an even number. Therefore, the final answer is 1503. The final answer is a whole number and has no remainder or a fraction.

This website will show the principles of solving Math problems in Arithmetic, Algebra, Plane Geometry, Solid Geometry, Analytic Geometry, Trigonometry, Differential Calculus, Integral Calculus, Statistics, Differential Equations, Physics, Mechanics, Strength of Materials, and Chemical Engineering Math that we are using anywhere in everyday life. This website is also about the derivation of common formulas and equations. (Founded on September 28, 2012 in Newark, California, USA)
Wednesday, May 7, 2014
Tuesday, May 6, 2014
More Cube Problems, 8
Category: Solid Geometry
"Published in Newark, California, USA"
Show that (a) the total surface of a cube is twice the square of its diagonal, (b) the volume of a cube is 1/9 √3 times the cube of its diagonal.
Solution:
To illustrate the problem, it is better to draw the figure as follows
Consider the lower base of a cube. Use Pythagorean Theorem in order to solve for the hypotenuse or the diagonal of the lower base as follows
If all the faces of a cube are perpendicular to each other, then all edges are perpendicular to each other also. Since c is located at the lower base of a cube, then c is perpendicular to x.
Use Pythagorean Theorem in order to solve for the diagonal of a cube as follows
The total area of a cube is
The volume of a cube is
Therefore,
(a)
(b)
"Published in Newark, California, USA"
Show that (a) the total surface of a cube is twice the square of its diagonal, (b) the volume of a cube is 1/9 √3 times the cube of its diagonal.
Solution:
To illustrate the problem, it is better to draw the figure as follows
![]() |
Photo by Math Principles in Everyday Life |
Consider the lower base of a cube. Use Pythagorean Theorem in order to solve for the hypotenuse or the diagonal of the lower base as follows
If all the faces of a cube are perpendicular to each other, then all edges are perpendicular to each other also. Since c is located at the lower base of a cube, then c is perpendicular to x.
Use Pythagorean Theorem in order to solve for the diagonal of a cube as follows
The total area of a cube is
The volume of a cube is
Therefore,
(a)
(b)
Monday, May 5, 2014
More Cube Problem, 7
Category: Solid Geometry, Trigonometry
"Published in Vacaville, California, USA"
The plane section ABCD shown in the figure is cut from a cube of edge a. Find the angle which the section ABCD makes with the lower base of the cube if D and C are each at the midpoint of an edge.
Solution:
To understand more the problem, it is better to label further the given figure as follows
Since the edges of a cutting plane which are AB and CD are parallel to the four parallel sides of a cube, then two triangles formed by a cutting plane with a cube are congruent.
Since the edges of a cube are perpendicular to each other, then two triangles are right triangles.
Therefore, the angle of a cutting plane with respect to the lower base of a cube is
or
"Published in Vacaville, California, USA"
The plane section ABCD shown in the figure is cut from a cube of edge a. Find the angle which the section ABCD makes with the lower base of the cube if D and C are each at the midpoint of an edge.
![]() |
Photo by Math Principles in Everyday Life |
Solution:
To understand more the problem, it is better to label further the given figure as follows
![]() |
Photo by Math Principles in Everyday Life |
Since the edges of a cutting plane which are AB and CD are parallel to the four parallel sides of a cube, then two triangles formed by a cutting plane with a cube are congruent.
Since the edges of a cube are perpendicular to each other, then two triangles are right triangles.
Therefore, the angle of a cutting plane with respect to the lower base of a cube is
or
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