( 2 + 4 + 6 + 8 + 10 ) - ( 1 + 2 + 3 + 4 + 5 ) = 15
= ( 10 + 10 + 10 ) - ( 10 + 5 ) = → primul mod
= 30 - 15 =
= 15
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( 2 + 4 + 6 + 8 + 10 ) - ( 1 + 2 + 3 + 4 + 5 ) = 15
= 2 × ( 1 + 2 + 3 + 4 + 5 ) - ( 10 + 5 ) = → al doilea mod
= 2 × 15 - 15 =
= 15 × ( 2 - 1 ) =
= 15