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2020 AMC 10A Problem 18

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2020 AMC 10A Problem 18AMC 10 Step by Step

Name: Date: September 13, 2026

Number Properties · difficulty 3 of 5 · about 4 min · position P16-20

Let $(a,b,c,d)$ be an ordered quadruple of not necessarily distinct integers, each one of them in the set $\{0,1,2,3\}.$ For how many such quadruples is it true that $a\cdot d-b\cdot c$ is odd? (For example, $(0,3,1,1)$ is one such quadruple, because $0\cdot 1-3\cdot 1 = -3$ is odd.)

A)
$48$
B)
$64$
C)
$96$
D)
$128$
E)
$192$

2020 AMC 10A Problem 18

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