START
LESSON
GO TO THE GAMES
Click on the correct answer.
You will see the left side of an equation. Then you will see and hear two possible answers for the right side of that equation.
Click on the correct answer.
There are 10 questions in this test.
to start the lesson
anonymous 🦊
"Two variables"
Elementary math lessons to learn
'Complements of number one' for 4th grade
4th grade / Decimals / Add decimals / Complements of number one
Decimal complements: complements of 1
Decimal complements refer to the process of finding the complement of a decimal number with respect to a target number. In this topic, complements to 1, complement means the value that, when added to the given decimal number, will result in a sum of 1.
To find the decimal complement to 1, you can follow these steps:
- Start with the given decimal number.
- Subtract the decimal number from 1.
- The result will be the decimal complement to 1.
For example, let's say we want to find the decimal complement to 1 of the number 0.75.
1 - 0.75 = 0.25
So, the decimal complement to 1 of 0.75 is 0.25.
Another example: Let's find the decimal complement to 1 of the number 0.412.
This is not as easy as the first example because the subtraction is harder:
1 - 0.412
Of course you can use a calculator to do this, but as mental arithmetic, the easiest way is to think of the digits after the point as a separate value, in this case 412. Because there are 3 digits, we subtract it from 1000, so we get 1000 - 412 = 588
Putting the decimal point back in, we can say:
1 - 0.412 = 0.588
So, the decimal complement to 1 of 0.412 is 0.588
With these interactive math lessons you will be learning "Complements of number one" from
4th grade / Decimals in 3 easy steps. The math in our lessons consists of 6 questions that ask you to identify the missing decimal complement to 1.
There are 3 easy math lesson activities in this "Complements of number one" tutorial. These activities progress step by step to help you the learner gradually master this math topic. The activities are based on "3 stage questioning", a method of learning that quickly and easily builds your confidence as you work through the short series of lessons that strengthen your knowledge of the math that you want to learn.
When you have completed the tutorial for a topic, you should try some of our games before finally doing the test for your chosen topic. See the Help box below for detailed instructions on how to use the lesson activities to help you learn your math more easily.
UXO * Duck shoot * The frog flies * Pong * Cat and mouse * The beetle and the bee
Rock fall * Four in a row * Sow grow * Choose or lose * Mix and match
How to use our tutorials to learn
'Complements of number one' for 4th grade
Introduction to the math topic
You start the tutorial with a lesson that introduces the math you will be learning. You will see a set of questions one at a time, and for each question you will see the written answer and also hear the answer to that question.
Repeat the question/answer by clicking on the brown speaker sign. Repeat the question/answer and expand the question graphic by clicking on the question box. Move between questions using the arrow buttons below the question. If there is additional information available for your chosen topic, the "i" button on the left upright bar will be brown on white. Click on the button to load the additional lesson information into the main interface.
Either / Or math lesson
This lesson moves on from the "Introduction" lesson and offers you two possible answers to each question. So, you will see a question then a voice will ask "Is this ... or is it ..." and you will have to choose which of the answers is the one that matches the question.
You choose an answer by clicking or tapping on one of the two answer boxes below the question. You can play the audio for each answer again by clicking on the speaker icon beside the written answer (if robot speech is available and enabled). The program will let you know each time whether you answered correctly. A star will light up red for a wrong answer or white/black for a correct answer.
This lesson asks you the questions in a random order compared to the introduction. At the end of the lesson, you can choose whether to repeat the lesson or move on to the next one.
What is it? math lesson
The final lesson of the tutorial shows you multiple possible answers for each question - you must choose the correct one. You are asked a question and below it are a list of two, three, or four possible written/numeric answers from this topic. Pressing the speaker icon will play the math audio for that answer.
For each picture, click on the answer that matches the question. The program will tell you whether you are right or not. As with the Either / Or activity a system of stars indicate your right and wrong answers. The What is it? lesson will show you all the questions you learned in the Introduction but in a random order.
When you complete the "What is it?" lesson, you can choose whether to go on to play some games with this topic, or whether you want to repeat some or all of the lesson activities in this tutorial. You should expect to get 80% of the answers correct in most of the activities before trying some of the Math games with this topic.
