2-min Fluency Warm-up — Mental math.
700 − 100 =
320 + 100 =
55 − 10 =
84 + 10 =
Problem Solving Strategy #4: Guess and Check
Make a smart guess, check if it works, then adjust!
Problem: Two numbers add up to 45. One number is 28. What is the other?
Guess: 17 → 28 + 17 = 45 ✓
Answer: 17
Problem: I think of a number. Add 30 and you get 85. What is it?
Guess: 55 → 55 + 30 = 85 ✓
Answer: 55
Make a guess, check it, adjust if needed.
Two numbers add up to 63. One is 38. What is the other?
My guess: → Check:
Answer:
A number plus 45 equals 91. What is the number?
My guess: → Check:
Answer:
Two numbers add up to 72. One is 29. What is the other?
My guess: → Check:
Answer:
Read carefully. Choose which strategy to use for each problem.
The class has 68 books. 35 are fiction and the rest are non-fiction. How many non-fiction?
Strategy I used: ____
My work:
non-fiction
I thought of a number. Add 27 and you get 64. What is my number?
Strategy I used: ____
My work:
number
Two Ways! Solve this problem two different ways — use two different strategies.
There are 53 kids on the playground. 26 go inside. How many are still outside?
Way 1 — strategy: ____
Answer:
Way 2 (another way) — strategy: ____
Answer:
Challenge Problem
Two numbers add up to 100. One number is 36 more than the other. What are the two numbers?
Strategy I chose: ____
Show your work:
My numbers: and