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LESSON
2nd grade / Addition / Mental calculations / 3-digit number plus multiple of 100
When we want to add a smaller number to a bigger number, there are sometimes shortcuts that make it easier. If one of the numbers is 100 or a multiple of 100, adding that number to another number just means increasing the hundreds column of the other number by the number of hundreds you are adding.
So, for instance, if you want to add:
657 + 200
all you need to do is add 2 to the hundreds column value which is 6, so you get 8 for the hundreds column. The rest of the other number stays the same, so the total addition looks like this:
657 + 200 = 857
In the same way, adding 419 and 400 gives:
419 + 400 = 819
It is the same idea if you want to add units to 3 digit numbers but this time you would add to the units column value by the number of units you want to add, so, for instance, 271 + 5 = 276 because all we had to do was add 5 to the units column value to get an answer.
With these interactive math lessons you will be learning "3-digit number plus multiple of 100" from
2nd grade / Addition in 3 easy steps. The math in our lessons consists of 6 questions that ask you to use mental calculations to add the given multiple of 100 to a three-digit number.
3 topics:
Three digit number plus units
Three digit number plus tens
Three digit number plus hundreds
Sometimes in math the most useful skill you can have is to be able to do complicated sums in your head, but don't worry, it's not magic, there's are techniques you can learn.
When we want to add a smaller number to a bigger number, there are sometimes shortcuts that make it easier. If the smaller number is 10 or a multiple of 10, adding that number to a bigger number just means increasing the tens column of the bigger number by the number of tens you are adding.
So, for instance, if you want to add:
30 + 248
all you need to do is add 3 to the tens column value which is 4, so you get 7 for the tens column. The rest of the big number stays the same, so the total addition looks like this:
30 + 248 = 278
It is the same idea if you want to add hundreds but this time you would add to the hundreds column value by the number of hundreds you want to add. Adding units is often just going to affect the units column, so for instance, 271 + 5 = 276 because all we had to do was add 5 to the units column value to get an answer.
There are 3 easy math lesson activities in this "3-digit number plus multiple of 100" 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.
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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.
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.
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.
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