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.
Example 1
What is 285 + 6?
Let's solve this with a number line. Start on the number 285 and then count on 6.
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:
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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.
First add the 5 to take you to the next ten (290).
285 + 5 = 290
Then add the 1.
290 + 1 = 291
Example 2
What is 422 + 4?
Let's use Base 10 this time:
How would you add a 3-digit number and a 1-digit number using the column method?
Example 3
What is 239 + 4?
Let's try using the column method to solve this question.
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