standard_description: Fluently multiply and divide within 100, using strategies such as the relationship between multiplication and division (e.g., knowing that 8 × 5 = 40, one knows 40 ÷ 5 = 8) or properties of operations. By the end of Grade 3, know from memory all products of two one-digit numbers.
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for subtracting multi-digit numbers when the minuend is a multiple of 100. These understandings help students develop fluency and will be helpful later in this lesson when students will need to be able to interpret student work and solve word problems that involve multi-digit numbers.
Launch
Display one expression.
“Give me a signal when you have an answer and can explain how you got it.”
Activity
1 minute: quiet think time
Record answers and strategy.
Keep expressions and work displayed.
Repeat with each expression.
Student Facing
Find the value of each expression mentally.
\(5,\!000 - 403\)
\(5,\!300 - 473\)
\(25,\!300 - 493\)
\(26,\!000 - 1,\!493\)
Student Response
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Activity Synthesis
“Did you find yourself always using an earlier expression to help you find the value of a new expression? Did you find yourself switching strategies at times?”
“Which expression did you find most challenging to reason about?” (Sample response:
\(26,\!000-1,\!493\)
because there were many zeros in the number being subtracted from.)


aligns: no