Logical Thinking Warmup
What is the number covered by the question mark (?)?
The answer is 5.
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1 solution
Let the numbers at the top, right and left vertices and the middle of the triangle be a , b , c and d respectively. We note from the first three triangles that a + b − c = d such that:
⎩ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎧ 3 + 8 − 5 = 6 9 + 3 − 5 = 7 3 + 9 − 4 = 8 ? + 8 − 4 = 9
⟹ ? = 9 − 8 + 4 = 5
From This, We Can Infer That
Left Number + Inside Triangle Number = Top Number + Right Number
Therefore, 4 + 9 = 13
13 - 8 = 5