Sum of first N natural numbers with alternate signs | Function to find the sum of first N natural numbers with alternate signs ; Stores sum of alternate sign of first N natural numbers ; If N is an even number ; Update alternateSum ; If N is an odd number ; Update alternateSum ; Driver Code
function alternatingSumOfFirst_N ( N ) { var alternateSum = 0 ; if ( N % 2 == 0 ) { alternateSum = ( - N ) / 2 ; } else { alternateSum = ( N + 1 ) / 2 ; } return alternateSum ; } var N = 6 ; document . write ( alternatingSumOfFirst_N ( N ) ) ;