This is an introduction to the least common multiple of two numbers. The term itself tells you what this means: we need to check the MULTIPLES of the two numbers, find the common ones, and choose the least of those. Examples make this idea clear.
In the ...

From Math Mammoth

The basics of the concept of the greatest common factor (GCF) of two numbers. The name itself explains what to do: find the factors of the two numbers, find the COMMON ones among them, and choose the greatest.
I go through several examples using this def...

From Math Mammoth

In this 2nd part, we find the GCF using the prime factorization of the numbers. This is a much faster and preferred way of finding the GCF when the numbers get larger.
I also tie this concept in with factoring and the distributive property. In algebra, w...

From Math Mammoth

To find all the prime factors of any number, we can use a factor tree. To start the factorization process, simply write the number as a product (as a multiplication) in any way you like (except 1 x the number). That gives you two "branches". Then factor t...

From Math Mammoth

To find all the prime factors of any number, we can use a factor tree. To start the factorization process, simply write the number as a product (as a multiplication) in any way you like (except 1 x the number). That gives you two "branches". Then factor t...

From Math Mammoth

I explain a systematic way of finding all the factors of a given number. Basically, we check whether numbers 2, 3, 4, 5, and so on are factors of the number, and every time we find a factor, we write the multiplication and write down both factors. Going t...

From Math Mammoth

I explain a systematic way of finding all the factors of a given number. Basically, we check whether numbers 2, 3, 4, 5, and so on are factors of the number, and every time we find a factor, we write the multiplication and write down both factors. Going t...

From Math Mammoth

I explain a systematic way of finding all the factors of a given number. Basically, we check whether numbers 2, 3, 4, 5, and so on are factors of the number, and every time we find a factor, we write the multiplication and write down both factors. Going t...

From Math Mammoth

In this lesson we have a chart for numbers 1-30, and I check whether each of them is divisible by 1, 2, 3, 4, 5, 6, 7, 8, and 9. The larger numbers didn't fit, but not to worry, our check is sufficient to find all the primes between 1 and 30: they are num...

From Math Mammoth

In this lesson we have a chart for numbers 1-30, and I check whether each of them is divisible by 1, 2, 3, 4, 5, 6, 7, 8, and 9. The larger numbers didn't fit, but not to worry, our check is sufficient to find all the primes between 1 and 30: they are num...

From Math Mammoth

In this lesson we have a chart for numbers 1-30, and I check whether each of them is divisible by 1, 2, 3, 4, 5, 6, 7, 8, and 9. The larger numbers didn't fit, but not to worry, our check is sufficient to find all the primes between 1 and 30: they are num...

From Math Mammoth

Volume (how much space something takes) is measured in CUBIC units - which are simply little cubes. If the edges those cubes are 1 inch each, we have one cubic inch. If they are 1 cm each, we have a one cubic centimeter, and so on.
Then we look at the vo...

From Math Mammoth

We look at two numerical (linear) patterns created by adding or subtracting the same number (the rule), and their graphs in the coordinate grid. For example, if we add 1 to the x-coordinate and add 2 to the y-coordinate, and plot the points, the resulting...

From Math Mammoth

In the first part of this lesson, I construct a histogram using ages of swimming club participants. Those get grouped into bins, and then it's easy to draw the histogram just like a bar graph, but the bars touch each other.
Secondly, we have data about g...

From Math Mammoth

What does the mean (average) of a data set actually signify? This lesson doesn't focus on HOW to calculate it (though I cover that too), but instead, presents several example problems that involve the arithmetic mean in some manner.
In the last problem ...

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I go through and solve two geometry problems here.
The first one involves finding the area of a frame. I show two methods for that. The second asks us to find both the area and the perimeter of a rectangular shape (polygon), when some of the side lengths...

From Math Mammoth

Both addition and subtraction have to do with parts and a total. We can draw a bar model to illustrate addition and subtraction equations, and vice versa: write various addition and subtraction sentences from the given bar model.
Secondly in this lesson ...

From Math Mammoth

We review basic concepts related to multiplication and division (for 5th grade math): both operations have to do with EQUAL GROUPS. Division sentences start with the TOTAL, whereas multiplication sentences (or equations) give us the total.
Some beginnin...

From Math Mammoth

Long division process is the same, whether the divisor has one or two digits, BUT with two-digit divisors, it helps to build a multiplication table (or list of multiples) of the divisor before starting the division.
In this lesson, we start out by a divi...

From Math Mammoth

A math lesson for 2nd grade. We use a time line or an "hour line" to figure out how many hours it is from one given time to another. When one of the times is AM and the other PM, we need to figure the elapsed time in two parts.
We also solve some word pr...

From Math Mammoth

This video lesson teaches children how to tell time using the expressions "past" and "till". We can tell the time in the format (hours:minutes), or we can tell how many minutes past the whole hour it is, or how many minutes till the next whole hour it is....

From Math Mammoth

Learn to tell the "tricky times" on an analog clock -- those near the next full hour (times with 45, 50 or 55 minutes). I use a clock with numbers for the minute hand to make it easier for students. In this lesson we focus on not getting fooled by the hou...

From Math Mammoth

Learn to tell time on an analog clock to the five-minute intervals. I use a clock that shows the numbers for the minute hand, written on the outside of the clock rim. Those numbers of course go by fives (you count by fives). So, the students can simply lo...

From Math Mammoth

We practice rounding 4-digit numbers to various places (to the nearest ten, nearest hundred, and nearest thousand). I explain a systematic method for rounding: draw a cutoff line right after the digit you're rounding to. Then look at the digit AFTER that ...

From Math Mammoth

We practice rounding 4-digit numbers to various places (to the nearest ten, nearest hundred, and nearest thousand). I explain a systematic method for rounding: draw a cutoff line right after the digit you're rounding to. Then look at the digit AFTER that ...

From Math Mammoth

Here are two money-related word problems for about 4th grade. The first one asks how many $0.89 toy figures you can get with $15, which would normally be solved with division, but here we solve it using doubling and estimation.
The second problem is a si...

From Math Mammoth

Here are two money-related word problems for about 4th grade. The first one asks how many $0.89 toy figures you can get with $15, which would normally be solved with division, but here we solve it using doubling and estimation.
The second problem is a si...

From Math Mammoth

Here are two money-related word problems for about 4th grade. The first one asks how many $0.89 toy figures you can get with $15, which would normally be solved with division, but here we solve it using doubling and estimation.
The second problem is a si...

From Math Mammoth

An easy lesson where we estimate products using rounding. The basic rule is to round in such a manner that makes it easy for YOU to multiply mentally. In other words, there are no "hard and fast" rules as to HOW exactly you round when estimating, because ...

From Math Mammoth

An easy lesson where we estimate products using rounding. The basic rule is to round in such a manner that makes it easy for YOU to multiply mentally. In other words, there are no "hard and fast" rules as to HOW exactly you round when estimating, because ...

From Math Mammoth

First in this lesson, we tackle a subtraction problem. I first estimate its result by rounding the numbers to the nearest hundred, then calculate the exact difference.
Secondly we solve a word problem without using exact calculations -- just estimation. ...

From Math Mammoth

First in this lesson, we tackle a subtraction problem. I first estimate its result by rounding the numbers to the nearest hundred, then calculate the exact difference.
Secondly we solve a word problem without using exact calculations -- just estimation. ...

From Math Mammoth

In this lesson, we first practice rounding money amounts to the nearest dollar or ten dollars. Then we estimate the total of a grocery bill using rounded numbers (rounding the individual items to the nearest dollar). The lesson is intended for about 4th g...

From Math Mammoth

In this lesson, we first practice rounding money amounts to the nearest dollar or ten dollars. Then we estimate the total of a grocery bill using rounded numbers (rounding the individual items to the nearest dollar). The lesson is intended for about 4th g...

From Math Mammoth

First we practice multiplying money amounts and estimating the final result. Secondly, I work through a word problem that involves money, using a bar model to help.
This video is meant for 4th grade math....

From Math Mammoth

First we practice multiplying money amounts and estimating the final result. Secondly, I work through a word problem that involves money, using a bar model to help.
This video is meant for 4th grade math....

From Math Mammoth

First we practice multiplying money amounts and estimating the final result. Secondly, I work through a word problem that involves money, using a bar model to help.
This video is meant for 4th grade math....

From Math Mammoth

Once students have learned about division, it is time to learn a bit about the order of operations. You can draw a "bubble" or a "cloud" around the operation to be done first! That will make it kind of fun. :) This lesson uses the four basic operations pl...

From Math Mammoth

Once students have learned about division, it is time to learn a bit about the order of operations. You can draw a "bubble" or a "cloud" around the operation to be done first! That will make it kind of fun. :) This lesson uses the four basic operations pl...

From Math Mammoth

We write simple expressions (number sentences) from the verbal description, using several operations and parenthesis. In other words, we need to take into account the order of operations here! For example, subtract 12 and 6, and multiply the result by 4....

From Math Mammoth

We write simple expressions (number sentences) from the verbal description, using several operations and parenthesis. In other words, we need to take into account the order of operations here! For example, subtract 12 and 6, and multiply the result by 4....

From Math Mammoth