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Watch: Adding one-digit and three-digit numbers

When you add a 1-digit number to a 3-digit number, the same rules apply as when you are adding a 1-digit number to a 1 or 2-digit number.

Number lines, partitioning, Base 10 and the column method can all be useful.

Learn more about adding a 1-digit to a 3-digit number in this video.

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Example 1

What is 285 + 6?

Let's solve this with a number line. Start on the number 285 and then count on 6.

A number line counting 6 places from 285 to 291.

Notice how both digits in the tens and ones have changed? That鈥檚 because you bridged a ten when six was added.

285 + 6 = 291

Another good way to solve the question is to partition the number 6:

Now that 6 has been partitioned into 5 and 1, you can use your number bond knowledge to add the 5 to reach the next ten, then add 1.

A number line counting 5 places from 285 to 290, and then another 1 place to 291

First add the 5 to take you to the next ten (290).

285 + 5 = 290

Then add the 1.

290 + 1 = 291

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Example 2

What is 422 + 4?

Let's use Base 10 this time:

422 + 4 = 426 represented with base 10 blocks

How would you add a 3-digit number and a 1-digit number using the column method?

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Example 3

What is 239 + 4?

Let's try using the column method to solve this question.

Image gallerySkip image gallerySlide 1 of 4, Write the question out like this, with the 4 underneath the 9 in the ones column. , Lay the question out like this, with the 4 underneath the 9 in the ones column.
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Activity

Quiz

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More on Adding and subtracting

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