Let’s use the take-apart strategy to subtract. Do you see any whole tens? Whole tens are numbers that have 0 in the ones place.
25 - 13 = ___
25 - 13 = ___
25 and 13 are non-whole tens because they do not have 0s in the ones place.
Let’s Learn!
How can I apply the take-apart strategy when subtracting two-digit numbers?
Goal:
Goal:
Think About It!
Goal: Can you take apart non-whole ten numbers?
There are 25 candles, and 13 are lit. Arianna wants to use mental math to find the number of candles she still needs to light. Mental math is done without writing down any numbers.
We can make a whole ten by taking apart 13.
Now, we can subtract the whole ten.
Do not forget to subtract the one-digit part.
Great job! You used the take-apart strategy to find the difference. Arianna still needs to light 12 candles.
Question:
We just used the subtract-in-parts strategy! Why is it helpful?
Subtracting in parts lets us subtract friendly numbers. Friendly numbers are easy to subtract. Whole tens and one-digit numbers are friendly!