1) S = 1 + 2 + 3 +.........+59
S = 59+58+57 +......+2 +1
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2S = 60 + 60 + 60 +........+60 = 59·60 S = 59·60/2 = 1770
2). S = 1+ 2+ 3 +......+ 180 = 180·181/2 = 16290
3) S = 2(1+2+3+......+128) = 2·128·129/2 = 16512
4) S = 3(1+2+3+.....+44) = 3·44·45/2 = 1980