The hash is neither required nor helpful.

my @change = (1.15, -0.1, 5.4, 1.03, -0.241);
my @numberofshares = (100, 400, 200, 300, 240);

my $product = 0;
for (0..$#change) {
    $product += $change[$_] * $numberofshares[$_];
}
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