Problem 4 · 2013 Math Kangaroo
Easy
Algebra & Patterns
place-valuesubstitution
Elisa wrote down a sum. The same digit is hidden under each black square. Which digit is it?
5■ + 5■ = 104
Show answer
Answer: A — 2
Show hints
Hint 1 of 3
Both hidden squares are the same digit, so the two numbers being added are exactly the same number.
Still stuck? Show hint 2 →
Hint 2 of 3
Two equal numbers add up to 104, so each number must be half of 104.
Still stuck? Show hint 3 →
Hint 3 of 3
Half of 104 is 52, so figure out which digit makes the number 52.
Show solution
Approach: two equal numbers make 104, so each is half of 104
- The two hidden numbers are the same, and together they make 104.
- Half of 104 is 52, so each number is 52, meaning the hidden digit turns 5? into 52.
- The hidden digit is 2, which is answer A.
Mark:
· log in to save