Răspuns:
ultimele doua cifre ale numarului dat = 80
Explicație pas cu pas:
u₂ (1x2x3x4x5+1x2x3x4x5x6+....+1x2x3x4x5x6x...x100) = ?
u₂(1x2x3x4x5) = 20
u₂(1x2x3x4x5x6) = 20
u₂(1x2x3x4x5x6x7) = 40
u₂(1x2x3x4x5x6x7x8) = 20
u₂(1x2x3x4x5x6x7x8x9) = 80
u₂(1x2x3x4x5x6x7x8x9x10) = 00
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u₂(1x2x3x4x5x6x...x100) = 00 =>
u₂ (1x2x3x4x5+1x2x3x4x5x6+....+1x2x3x4x5x6x...x100) =
= u₂(20+20+40+20+80) = 80
